Isn’t about taking church to be best (6)
I believe the answer is:
nicest
'be best' is the definition.
(I've seen this before)
'isn't about taking church' is the wordplay.
'about' indicates anagramming the letters.
'taking' is an insertion indicator.
'church' becomes 'CE' (abbreviation for Church of England).
'isnt' anagrammed gives 'nist'.
'nist' going around 'ce' is 'NICEST'.
'to' is the link.
(Other definitions for nicest that I've seen before include "Most acceptable" , "Most agreeable" , "Most appealing" , "Insect (anag)" , "Sin etc (anag)" .)