With bitterness, start to admonish councillor doing nothing (7)
I believe the answer is:
acridly
'with bitterness' is the definition.
Both the definition and answer are adverbs.
Perhaps you can see a link between them that I can't see?
'start to admonish councillor doing nothing' is the wordplay.
'start to' indicates taking the first letters.
'councillor' becomes 'cr' (abbreviation).
'doing nothing' becomes 'idly' (I am not sure about this - if you are sure you should believe this answer much more).
The initial letter of 'admonish' is 'a'.
'a'+'cr'+'idly'='ACRIDLY'
Can you help me to learn more?
(Another definition for acridly that I've seen is " Corrosively".)