Leading character is somewhat lecherous (4)
I believe the answer is:
hero
'leading character' is the definition.
'somewhat lecherous' is the wordplay.
'somewhat' indicates a hidden word.
'HERO' can be found hidden inside 'lecherous'.
'is' acts as a link.
(Other definitions for hero that I've seen before include "chap we revere" , "Exceptionally brave person" , "Person lauded for bravery" , "Courageous man" , "Chief male character in story or film - probably very brave" .)