Support vehicle returning to get top man (7)
I believe the answer is:
backing
'support' is the definition.
(I know that support can be written as backing)
'vehicle returning to get top man' is the wordplay.
'vehicle' becomes 'cab' (cab is a kind of vehicle).
'returning' is a reversal indicator.
'to get' means one lot of letters go next to another.
'top man' becomes 'king' (male ruler).
'cab' back-to-front is 'bac'.
'bac'+'king'='BACKING'
(Other definitions for backing that I've seen before include "funds?" , "Support" , "gambling" , "Supporting or betting on" , "change of wind" .)