Flaky nurses object bitterly (10)
I believe the answer is:
scathingly
'bitterly' is the definition.
(thesaurus)
'flaky nurses object' is the wordplay.
'flaky' becomes 'scaly' (I can't justify this - if you can you should believe this answer much more).
'nurses' indicates putting letters inside.
'object' becomes 'thing' (thing is a kind of object).
'scaly' enclosing 'thing' is 'SCATHINGLY'.
Can you help me to learn more?
I've seen this clue in The Independent.
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