Most of difficult dispute will produce distress (6)
I believe the answer is:
harrow
'distress' is the definition.
(something harrowing is distressing)
'most of difficult dispute' is the wordplay.
'most of' means to remove the last letter.
'difficult' becomes 'hard' (synonyms).
'dispute' becomes 'row' (row is a kind of dispute).
'hard' with its final letter taken off is 'har'.
'har'+'row'='HARROW'
'will produce' is the link.
(Other definitions for harrow that I've seen before include "Till" , "Soil-breaker; school" , "Torment (at public school?)" , "Agricultural frame for breaking up soil" , "It breaks up clods and covers seeds" .)