Outlaw historically needing to gain time (7)
I believe the answer is:
attaint
'outlaw historically' is the definition.
(to subject to attainder, historical punishment)
'to gain time' is the wordplay.
'to gain' becomes 'attain' (synonyms).
'time' becomes 't' (abbreviation).
'attain'+'t'='ATTAINT'
'needing' acts as a link.
(Other definitions for attaint that I've seen before include "Condemn" , "The old convict" .)