Skirmish in Sussex town (6)
I believe the answer is:
battle
I believe this is a double definition.
'skirmish' is the first definition.
(I've seen this before)
'sussex town' is the second definition.
(I've seen this before)
'in' acts as a link.
(Other definitions for battle that I've seen before include "Action" , "war" , "Ben < 's engagement" , "Major engagement" , "Encounter" .)