Trendy church's leader, silly rector is wrong (9)
I believe the answer is:
incorrect
'is wrong' is the definition.
('incorrect' can be a synonym of 'wrong')
'trendy church's leader silly rector' is the wordplay.
'trendy' becomes 'in'.
'leader' says to take the initial letters.
'silly' is an anagram indicator.
The first letter of 'churchs' is 'c'.
'rector' anagrammed gives 'orrect'.
'in'+'c'+'orrect'='INCORRECT'
(Other definitions for incorrect that I've seen before include "Not accurate" , "Place of refuge" , "False, wrong" , "Erroneous" .)