Disjointed fight with outsiders in party (7)
I believe the answer is:
scrappy
'disjointed' is the definition.
(I've seen this before)
'fight with outsiders in party' is the wordplay.
'fight' becomes 'scrap' (I've seen this before).
'with' says to put letters next to each other.
'outsiders in' suggests removing the centre.
'party' with its middle taken out is 'py'.
'scrap'+'py'='SCRAPPY'
(Other definitions for scrappy that I've seen before include "Fragmentary" , "Disjointed" , "disorganised" , "Fragmented" .)