Accomplished advance or defeat? (8)
I believe the answer is:
overcome
'defeat?' is the definition.
(overcoming is a kind of defeating)
'accomplished advance' is the wordplay.
'accomplished' becomes 'over' (I've seen this before).
'advance' becomes 'come' (I've seen this in other clues**).
'over'+'come'='OVERCOME'
'or' is the link.
(Other definitions for overcome that I've seen before include "Broken" , "Deal successfully with difficulties" , "Defeat (someone)" , "hammer" , "Succeed in dealing with difficulties" .)