Priest likely to be flexible (7)
I believe the answer is:
pliable
'flexible' is the definition.
(synonyms)
'priest likely' is the wordplay.
'priest' becomes 'p' (ecclesiastical abbreviation).
'likely' becomes 'liable' (similar in meaning).
'p'+'liable'='PLIABLE'
'to be' acts as a link.
(Other definitions for pliable that I've seen before include "accommodating" , "Flexible" , "Easily bent" , "easily influenced" , "Elastic" .)