Interrupted brother gaining knowledge (6)
I believe the answer is:
broken
'interrupted' is the definition.
('broken' can be a synonym of 'interrupted')
'brother gaining knowledge' is the wordplay.
'brother' becomes 'bro'.
'gaining' says to put letters next to each other.
'knowledge' becomes 'ken' (ken is a kind of knowledge**).
'bro'+'ken'='BROKEN'
(Other definitions for broken that I've seen before include "If it's not ..., don't fix it" , "Interrupted; inoperative" , "Bust" , "Smashed, in pieces" , "Fractured, damaged" .)