It may be below a crest (5)
I believe the answer is:
motto
'it may be below a crest' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for motto that I've seen before include "Catchphrase" , "Phrase in a Christmas cracker" , "Phrase to express character" , "Recurring musical phrase" , "(Family) maxim" .)