Former lover, with skill, turning over (5)
I believe the answer is:
extra
'over' is the definition.
(extra can mean left over)
'former lover with skill turning' is the wordplay.
'former lover' becomes 'ex' (an ex-lover).
'with' says to put letters next to each other.
'skill' becomes 'art' (both can mean a talent).
'turning' says the letters should be written in reverse.
'art' backwards is 'tra'.
'ex'+'tra'='EXTRA'
(Other definitions for extra that I've seen before include "Auxiliary" , "walk-on part" , "Taxer (anag.)" , "Additional, like non-speaking actor" , "Especially" .)