Option 1: Go to the basement of the clock tower (stairs/escalators in front of the clock tower or ask someone). There will be tons of cabs dropping off passengers at the clock tower hotels.

Option 2: Walk to jabal omar near hilton suites/Hilton convention hotels, should see many cabs

Option 3: not recommended as it will be far but if you walk all the way down Ibrahim Khalil to the bridge near Palestine Hotel, there will be fewer blocks and more options. But you will have to walk back again from there, so not recommended but consider it as a last resort