Reveal mother's brothers split in the past (7)
I believe the answer is:
uncover
'reveal mother's' is the definition.
'uncover' can be an answer for 'reveal' (synonyms). I am not certain of the 'mother's' bit.
'brothers split in the past' is the wordplay.
'brothers split' becomes 'unc' (I can't justify this - if you can you should believe this answer much more).
'in the past' becomes 'over' (both can mean finished or completed).
'unc'+'over'='UNCOVER'
Can you help me to learn more?
(Other definitions for uncover that I've seen before include "Strip off" , "show?" , "bare" , "Expose, unveil" , "make a revelation" .)