Most of the dispute with cast (5)
I believe the answer is:
throw
'cast' is the definition.
('throw' can be a synonym of 'cast')
'most of the dispute' is the wordplay.
'most of' means to remove the last letter.
'dispute' becomes 'row' (I've seen this before).
'the' with its last letter removed is 'th'.
'th'+'row'='THROW'
'with' acts as a link.
(Other definitions for throw that I've seen before include "Deliberately lose" , "Chuck - confuse" , "Toss" , "Confuse - cast" , "blanket" .)