Wrong one can upset member of the clergy (10)
I believe the answer is:
inaccurate
'wrong' is the definition.
(I've seen this before)
'one can upset member of the clergy' is the wordplay.
'one' becomes 'i' (Roman numeral).
'upset' shows that the letters should be reversed in order.
'member of the clergy' becomes 'curate' (I've seen this before).
'can' written backwards gives 'nac'.
'i'+'nac'+'curate'='INACCURATE'
(Other definitions for inaccurate that I've seen before include "wrong" , "not hitting all the right notes?" , "Unreliable" .)