Getting rid of top motorsport group (6)
I believe the answer is:
firing
'getting rid of' is the definition.
'top motorsport group' is the wordplay.
'top motorsport' becomes 'fi' (resembles F1, Formula 1).
'group' becomes 'ring'.
'fi'+'ring'='FIRING'
(Other definitions for firing that I've seen before include "Discharging, sacking" , "Discharging a gun" , "Shooting; sacking" , "Dismissing" , "Dismissal" .)