Reject managed without small motor (7)
I believe the answer is:
discard
'reject' is the definition.
(I've seen this before)
'managed without small motor' is the wordplay.
'managed' becomes 'did' ('do' can mean 'manage' as in 'do without').
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'small' becomes 's' (abbreviation - e.g. clothes size).
'motor' becomes 'car' (informal term for car).
's'+'car'='scar'
'did' placed around 'scar' is 'DISCARD'.
(Other definitions for discard that I've seen before include "bin" , "Get rid of" , "Throw away or cast off" , "Shed" , "Jettison" .)