Sacked left-winger receiving support (6)
I believe the answer is:
raided
'sacked' is the definition.
'left-winger receiving support' is the wordplay.
'left-winger' becomes 'red' (red is a kind of left-winger).
'receiving' is an insertion indicator.
'support' becomes 'aid' ('aid' can be a synonym of 'support'**).
'red' placed around 'aid' is 'RAIDED'.
(Other definitions for raided that I've seen before include "Made a sudden surprise attack on" , "Attacked" , "Entered a territory and took spoils" .)