Bit of fruit leading to sinful occasion's a banana skin (7)
I believe the answer is:
pitfall
'a banana skin' is the definition.
(banana skin can mean a pitfall or hazard)
'bit of fruit leading to sinful occasion's' is the wordplay.
'bit of fruit' becomes 'pit' (stone of a fruit).
'leading to' is a charade indicator (letters next to each other) (some letters go before or lead others).
'sinful occasion' becomes 'fall' (the fall in the garden of Eden).
'pit'+'fall'='PITFALL'
(Other definitions for pitfall that I've seen before include "Unexpected difficulty or danger" , "Hidden danger or difficulty" , "Unexpected problem" , "Trap in the form of a concealed hole" , "Unsuspected danger or difficulty - for miner?" .)