One cleric, no learner, around brotherhood to be bitter (7)
I believe the answer is:
acerbic
'be bitter' is the definition.
(synonyms)
'one cleric no learner around brotherhood' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'no' suggests deleting specific letters.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'around' is an insertion indicator.
'brotherhood' becomes 'b' (this might be a standard abbreviation which I don't know about).
'cleric' with 'l' taken out is 'ceric'.
'ceric' enclosing 'b' is 'cerbic'.
'a'+'cerbic'='ACERBIC'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for acerbic that I've seen before include "Bitter, sour" , "Cutting" , "Sarcastic" , "Astringent in tone" , "Bitter-tasting" .)