Rose & Nat bullied Polly (7)
I believe the answer is:
senator
'polly' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'rose nat bullied' is the wordplay.
'bullied' indicates anagramming the letters.
'rose'+'nat'='rosenat'
'rosenat' anagrammed gives 'SENATOR'.
Can you help me to learn more?
(Other definitions for senator that I've seen before include "Upper house US Congressman" , "Legislator -- treason (anag)" , "Upper House member involved in treason" , "Roman legislator" , "Member of Upper House engaged in treason" .)