Quietly punished errant lover (7)
I believe the answer is:
partner
'lover' is the definition.
(lover can mean a romantic or sexual partner)
'quietly punished errant' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'punished' is an anagram indicator.
'errant' is an anagram of 'artner'.
'p'+'artner'='PARTNER'
(Other definitions for partner that I've seen before include "One sharing home or business" , "south to north, perhaps" , "Spouse or business collaborator" , "A person dancing with another" , "Significant other" .)