Combat -- panic right away (5)
I believe the answer is:
fight
'combat' is the definition.
('fight' can be a synonym of 'combat')
'panic right away' is the wordplay.
'panic' becomes 'fright' (I've seen this before).
'right' becomes 'r' (common abbreviation).
'away' suggests deleting specific letters.
'fright' with 'r' taken away is 'FIGHT'.
(Other definitions for fight that I've seen before include "Attack or engage in combat" , "Bundle" , "Struggle; quarrel" , "Campaign against - quarrel" , "Come to blows" .)