Disagreements in first form (5)
I believe the answer is:
rifts
'disagreements' is the definition.
(I've seen this in another clue)
'first form' is the wordplay.
'form' indicates anagramming the letters (another form of the letters).
'first' is an anagram of 'RIFTS'.
'in' acts as a link.
(Other definitions for rifts that I've seen before include "Schisms" , "Splits" , "differences ..." , "Breaks, severances" , "Clefts or fissures." .)