Condition escalated on discharge (4)
I believe the answer is:
fire
'discharge' is the definition.
('fire' can be a synonym of 'discharge')
'condition escalated on' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for fire that I've seen before include "Trigger" , "Let off" , "See 5" , "cut" , "Dismiss; bake in a kiln" .)