Conflict gets energy to erode (4)
I believe the answer is:
wear
'to erode' is the definition.
(I've seen this in another clue)
'conflict gets energy' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'gets' is an insertion indicator (gets can mean captures or absorbs).
'energy' becomes 'e' (physics symbol as in E=mc2).
'war' going around 'e' is 'WEAR'.
(Other definitions for wear that I've seen before include "brook" , "Durability" , "Northern river - sport" , "Have on - deteriorate from constant use" , "fashion" .)