Small child's vehicle runs forward (7)
I believe the answer is:
striker
'forward' is the definition.
(forward can mean a football striker)
'small child's vehicle runs' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'child's vehicle' becomes 'trike' (tricycle).
'runs' becomes 'r' (cricket abbreviation).
's'+'trike'+'r'='STRIKER'
(Other definitions for striker that I've seen before include "One refusing to work - rings the bell" , "one who's out?" , "A forward on a soccer team" , "disaffected employee" , "One not working" .)