The snag about a guy going to church (5)
I believe the answer is:
catch
'the snag' is the definition.
(thesaurus)
'a guy going to church' is the wordplay.
'a guy' becomes 'cat' (I've seen this in other clues).
'going to' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'cat'+'ch'='CATCH'
'about' is the link.
(Other definitions for catch that I've seen before include "Snag - trap" , "Be in time to see" , "Ensnare" , "Trap - hear - contract" , "Apprehend - funny song" .)