Report of engine trouble — sponsor getting sack (8)
I believe the answer is:
backfire
'report of engine trouble' is the definition.
(car engine noise - 'report' can mean a loud noise)
'sponsor getting sack' is the wordplay.
'sponsor' becomes 'back'.
'getting' means one lot of letters go next to another.
'sack' becomes 'fire' (synonyms).
'back'+'fire'='BACKFIRE'
(Other definitions for backfire that I've seen before include "Be self-defeating" , "explosion" , "Boomerang" , "Rebound on oneself" , "Come home to roost" .)