Leader of delegation is member to win over (6)
I believe the answer is:
disarm
'win over' is the definition.
(both can mean to overcome an opponent)
'leader of delegation is member' is the wordplay.
'leader of' suggests taking the first letters.
'member' becomes 'arm' (member can mean a limb).
The initial letter of 'delegation' is 'd'.
'd'+'is'+'arm'='DISARM'
'to' acts as a link.
(Other definitions for disarm that I've seen before include "Deprive of weapons or win over" , "Take away weapons or make less angry" , "Take weapons from or charm" , "Abandon weapons" , "Give up weapons" .)