Potential source of explosion toppling bloody leader (7)
I believe the answer is:
warhead
'potential source of explosion' is the definition.
(a warhead might explode)
'toppling bloody leader' is the wordplay.
'toppling' shows that the letters should be reversed in order (in a down clue, letters topple over).
'bloody' becomes 'raw' (as in raw meat).
'leader' becomes 'head' (head is a kind of leader).
'raw' in reverse letter order is 'war'.
'war'+'head'='WARHEAD'
(Other definitions for warhead that I've seen before include "explosive container" , "Explosive part of a weapon" , "Explosive missile part" , "Charge" , "Missile's explosive" .)