Scrap with priest over English falsehood (5,3)
I believe the answer is:
white lie
'falsehood' is the definition.
(I have seen 'Minor falsehood ' mean 'white lie' so perhaps 'falsehood' could also mean 'white lie')
'scrap with priest over english' is the wordplay.
'scrap with' becomes 'whit' (both can mean a tiny amount. I am not sure about the 'with' bit.).
'priest' becomes 'eli' (biblical figure).
'over' is a charade indicator (letters next to each other).
'english' becomes 'e' (abbreviation).
'whit'+'eli'+'e'='WHITE LIE'
(Other definitions for white lie that I've seen before include "A trivial fib" , "pardonable offence" , "An unimportant departure from of the truth" , "Harmless untruth" , "when a tactful comment is required" .)