Sussex town cricketer let out (6)
I believe the answer is:
battle
'sussex town' is the definition.
(I've seen this before)
'cricketer let out' is the wordplay.
'cricketer' becomes 'bat' (I've seen this before).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'let' is an anagram of 'tle'.
'bat'+'tle'='BATTLE'
(Other definitions for battle that I've seen before include "'The race is not to the swift, nor the ... to the strong'" , "Military engagement" , "Ben < 's engagement" , "Military conflict" , "Conflict, fight" .)