Repulsive leader leads an unspecified number (7)
I believe the answer is:
noisome
'repulsive' is the definition.
(I've seen this in another clue)
'leader leads an unspecified number' is the wordplay.
'leader leads' becomes 'noi' (I am not sure about this - if you are sure you should believe this answer much more).
'an unspecified number' becomes 'some' (I've seen this before).
'noi'+'some'='NOISOME'
Can you help me to learn more?
(Other definitions for noisome that I've seen before include "Harmful to health; disgusting" , "Foul-smelling - semi-Ono (anag)" , "Disagreeable, unpleasant" , "Foul-smelling, noxious" , "noxious smells" .)