Surviving custom that's a bit more licentious (5)
I believe the answer is:
relic
'surviving custom' is the definition.
(I've seen this before)
'a bit more licentious' is the wordplay.
'a bit' indicates a hidden word (the answer is formed by a bit of the clue).
'RELIC' is hidden within 'more licentious'.
'that's' acts as a link.
(Other definitions for relic that I've seen before include "Holy remnant" , "Surviving artefact" , "Long-surviving object" , "Revered religious remnant" , "precious object" .)