Party held for one of Arthur's knights (7)
I believe the answer is:
galahad
'one of arthur's knights' is the definition.
(I've seen this before)
'party held' is the wordplay.
'party' becomes 'gala' (I've seen this in another clue).
'held' becomes 'had' ('have' can be a synonym of 'hold').
'gala'+'had'='GALAHAD'
'for' is the link.
(Other definitions for galahad that I've seen before include "Noble fellow" , "Errant fellow" , "K" , "Person of great nobility" , "One of Arthur's knights" .)