Opposing cheat after one's queen returns (9)
I believe the answer is:
resisting
'opposing' is the definition.
(resisting is a kind of opposing)
'cheat after one's queen returns' is the wordplay.
'cheat' becomes 'sting' (sting is a kind of cheat**).
'after' says to put letters next to each other.
'one's' becomes 'is' (Roman numeral).
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'returns' says the letters should be written backwards.
'is'+'er'='iser'
'iser' written backwards gives 'resi'.
'sting' after 'resi' is 'RESISTING'.
(Other definitions for resisting that I've seen before include "Refraining from" , "smart, that!" , "Withstanding" .)