Reject managed to conceal stigma (7)
I believe the answer is:
discard
'reject' is the definition.
(I've seen this before)
'managed to conceal stigma' is the wordplay.
'managed' becomes 'did' ('do' can mean 'manage' as in 'do without').
'to conceal' indicates putting letters inside.
'stigma' becomes 'scar' (I've seen this before).
'did' placed around 'scar' is 'DISCARD'.
(Other definitions for discard that I've seen before include "bin" , "Get rid of" , "Jettison" , "Throw away or cast off" , "Reject" .)