Medal winner, one on the other side (8,5)
I believe the answer is:
victoria cross
'medal' is the definition.
(Victoria Cross is an example)
'winner one on the other side' is the wordplay.
'winner' becomes 'victor' ('victor' can be a synonym of 'winner').
'one' becomes 'i' (Roman numeral).
'on the other side' becomes 'across' (I've seen this before).
'victor'+'i'+'across'='VICTORIA CROSS'
(Other definitions for victoria cross that I've seen before include "epitome of bravery" , "award" , "VC in full" , "Military medal" , "heroic achievement" .)