Craving sex before church (4)
I believe the answer is:
itch
'craving' is the definition.
(thesaurus)
'sex before church' is the wordplay.
'sex' becomes 'it' (a common euphemism).
'before' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'it'+'ch'='ITCH'
(Other definitions for itch that I've seen before include "Skin sensation; desire" , "Hankering" , "Craving" , "Irritating feeling on the skin" , "Prickle" .)