Complaint from lecturer at university backed leaders of Student Union (5)
I believe the answer is:
lupus
'complaint' is the definition.
(I've seen this before)
'lecturer at university backed leaders of student union' is the wordplay.
'lecturer' becomes 'l'.
'at university' becomes 'up'.
'backed' is a reversal indicator.
'leaders of' says to take the initial letters.
The initial letters of 'student union' is 'su'.
'su' reversed gives 'us'.
'l'+'up'+'us'='LUPUS'
'from' is the link.
(Other definitions for lupus that I've seen before include "[CONSTELLATION]" , "Complaint" , "Possibly, first Roman wet nurse" , "Skin problem" , "Skin disease" .)