Support resistance with collaborator and some ammunition (5,5)
I believe the answer is:
rally round
'support' is the definition.
(I've seen this before)
'resistance with collaborator and some ammunition' is the wordplay.
'resistance' becomes 'r' (electronics abbreviation).
'with' is a charade indicator (letters next to each other).
'collaborator' becomes 'ally'.
'and' means one lot of letters go next to another.
'some ammunition' becomes 'round' (round is a kind of ammunition).
'r'+'ally'+'round'='RALLY ROUND'
(Other definitions for rally round that I've seen before include "Pick up" , "Offer support" .)