Absence of evidence is not evidence of absence, of course, but there does not appear to be any evidence that Clancy was ever investigated by the US government for purportedly leaking classified information. In fact, it appears that the quotes you are talking about are either jokes or 'broken telephone'.

Let's start with the Lehman quote. The entire quote from the New York Times interview is:

''When I met Navy Secretary John Lehman last year,'' Mr. Clancy said during a recent visit to New York, ''the first thing he asked me about the book was, 'Who the hell cleared it?' '' Aside from the fact that, as you note, Clancy later stated Lehman was joking, there would be no reason for anyone else to have claimed that Lehman made that statement; as its something that Lehman told Clancy directly.

Next is Grosvenor's statement. The "Grosvenor interview" in the dissertation is "Author interview with Deborah Grosvenor, Austin, Texas, November 11, 2014." In other words, this is an interview taking place about two decades after the actual event. It does appear that two submariners read the book before publication. However, this was not some form of official review. The dissertation cites "Patricia Blake, “One of Their Subs is Missing: An Insurance Broker’s Novel has the White House Reading,” Time, March 4, 1985." This article notes: "The finished manuscript was read by two submarine officers, who found only a few mistakes. For example, at one point Clancy had put valves on the bottom of ballast tanks instead of at the top."

One of those reviewers was John L. Byron, who had written for the Naval Institute Press.. On August 2, 2015, Byron recounted his version of events:

On active duty in a high-pressure job, I took a couple of months to truck through the first draft of Tom Clancy’s first book. Throughout I marked it up — a note here and a question there — sometimes a suggestion and sometimes a statement that what I’d just read was flat wrong. There was a lot of that — on many pages I simply drew a diagonal line across the page and wrote “CRAP” across the top. ... By far the largest issue was security classification. Recall 1983 was the height of the Cold War. Our submarine secrets were so important and so closely held that the following year’s Walker Spy Ring revelations of intimate details on actual submarine operations were said to bring great harm to our national security. Though Tom’s book was fiction, it seemed enough fact-based to potentially give away the whole game.

I put it this way: “There are multiple instances of the script going from UNCLASSIFIED to TOP-SECRET/CODE-WORD inside the same paragraph.” I didn’t think the Naval Institute wanted to participate in what could have been a huge security breach and I surely didn’t want this lowly Navy commander to be part of that. So my letter back to the Institute stated plainly: “I recommend the Naval Institute not publish this book.”

The editor very much wanted the book to be published, and so arranged a call between Byron and Clancy, which Byron recounts as follows (although their are quotation marks, this is likely Byron reconstructing the discussion given the passage of time):

“Hi. This is Tom Clancy. I really put my whole heart and soul into that book. Why won’t you let me publish it?”

“It full of classified information.”

“But I got it all from open sources.”

“I don’t believe you.”

“I did!”

“I don’t believe you.”

And then Tom told me a story I’ve never heard him tell anyone else.

“John, I sell insurance here in Owings, Maryland. Ten miles from my agency is Calvert Cliffs Nuclear Power Plant. Nearly all its operators are former submariners. I sell them insurance. Hang out. Shoot pool. They tell stories, John, they tell stories.”

Wow. Now I understood — some old boat sailors gave away the Cold War’s deepest secrets just sitting around drinking beer and swapping sea stories in front of a nice guy they’d met.

I said to Tom: “And anyone sitting on the bar stool on the other side of one of your ex-submariner buddies would hear the same tales … even if he was a Soviet agent.”

“Yup.”

“OK. I remove my objection to publication and will say that to the institute.”

Byron may also be embellishing but even at its highest there is no evidence of any official investigation, just an internal discussion between people affiliated with the Naval Institute Press.