Exposes organisation to first minister's questions (7)
I believe the answer is:
unmasks
'exposes' is the definition.
(unmasking is a kind of exposing)
'organisation to first minister's questions' is the wordplay.
'organisation' becomes 'UN' (UN is an example).
'to first minister's' becomes 'm' (1st letter of 'minister').
'questions' becomes 'asks' (as in asking a question).
'un'+'m'+'asks'='UNMASKS'
(Other definitions for unmasks that I've seen before include "Exposes, shows up" , "Removes domino" , "Exposes, removes disguise" , "lays oneself open" , "Reveals the true nature of" .)