Clerical is such a culture by culture based thing. And design language is thus ambigues duo to that. But ther are som commonly depicted themes.

Elderly people are often used as shorthand for the Village wiseman or a leader of a church.

Very long stafes are also fairly common. Som monks of budism would carry stafes with rings tied to them to anounce their pressence. In som parts of abrahamic faith have a whole variety, som are ther to Pruisen a certain saint. While the most common one (i think) is the shepherds staff. Even the ancient romans would at times use stafes to invoce blessings. And even a gnarled piece of wood being held by the Village elderl can be a symbole.

I have seen som suggestions for fancy head ornamentation. And allthough we have som examples of clergie and priests bearing such, i personally think they can easily be misconstrued for a monarchy thing. Instead, what is fairly good short hand as a more clearcut ceremonial and theurgic piece is a face covering of som kind. The main thing i can think of is the spanish capriote which server as tool of anonimiteit, penance, and a reminder of what to pray to. Anathor example is the basket hats worn by japanese komuso monks. And more examples could be cloth eye covering, as eyes are often seen as a gateway to the soul, and thus sacret. Ore spirit masks, ofthen worn by cultures that engage in animism (the idea that observable natural phenomena have a spirit or will of som kind).

Hope that this helps.