After party battle to get soup (8)
I believe the answer is:
consomme
'soup' is the definition.
(consomme is a kind of soup)
'after party battle' is the wordplay.
'after' means one lot of letters go next to another.
'party' becomes 'con' (abbreviation for Conservative Party).
'battle' becomes 'Somme' (Battle of the Somme in WW1).
'con' put next to 'somme' is 'CONSOMME'.
'to get' acts as a link.
(Other definitions for consomme that I've seen before include "Clear soup usually of beef, veal or chicken" , "Clear initial course" , "Clear soup made with concentrated stock" , "Clear meaty soup" , "Liquid food" .)