Expel Open University student leaders (4)
I believe the answer is:
oust
'expel' is the definition.
(I know that expel can be written as oust)
'open university student leaders' is the wordplay.
'open university' becomes 'OU'.
'student leaders' becomes 'st' (I can't justify this - if you can you should believe this answer much more).
'ou'+'st'='OUST'
Can you help me to learn more?
(Other definitions for oust that I've seen before include "Get rid of" , "Remove from a position or office" , "Force from office" , "Expel (from a place)" , "Turf out" .)