Do go on about Queen favourite (10)
I believe the answer is:
perpetrate
'do' is the definition.
(I've seen this before)
'go on about queen favourite' is the wordplay.
'go on' becomes 'prate' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'favourite' becomes 'pet' (synonyms).
'er'+'pet'='erpet'
'prate' enclosing 'erpet' is 'PERPETRATE'.
(Other definitions for perpetrate that I've seen before include "Commit (a bad action)" , "Commit (crime)" , "Be responsible for" , "Carry out, commit" , "Act" .)