Second this fellow's manuscript about Conservative rifts (7)
I believe the answer is:
schisms
'rifts' is the definition.
(I've seen this in another clue)
'second this fellow's manuscript about conservative' is the wordplay.
'second this' becomes 's' (this could be a standard abbreviation which I don't know about).
'fellow's' becomes 'his' (belonging to a man).
'manuscript' becomes 'ms' (abbreviation for manuscript).
'about' says to put letters next to each other.
'conservative' becomes 'C' (UK political abbreviation).
'his'+'ms'='hisms'
'hisms' put after 'c' is 'chisms'.
's'+'chisms'='SCHISMS'
Can you help me to learn more?
(Other definitions for schisms that I've seen before include "Breaches in the church" , "Religious disunities" , "Breaches in churches" .)