University acceptable for workers’ group (5)
I believe the answer is:
union
'workers' group' is the definition.
(I've seen this before)
'university acceptable' is the wordplay.
'university' becomes 'uni' (informal abbreviation).
'acceptable' becomes 'on' (as opposed to not on, unacceptable).
'uni'+'on'='UNION'
'for' is the link.
(Other definitions for union that I've seen before include "The USA in the USA" , "Amalgamation" , "Workers' federation" , "Marriage; pipe joint" , "The joining of two or more together" .)