He'd support a fuel cut (6)
I believe the answer is:
gashed
'cut' is the definition.
(synonyms)
'he'd support a fuel' is the wordplay.
'support' is a charade indicator (letters next to each other) (in a down clue, some letters hold others up).
'a fuel' becomes 'gas' (gas is a fuel).
'hed' after 'gas' is 'GASHED'.
(Other definitions for gashed that I've seen before include "Deeply cut" , "Wounded" , "Cut open" .)