Pitch university against piece workers (7)
I believe the answer is:
bitumen
'pitch' is the definition.
(thesaurus)
'university against piece workers' is the wordplay.
'university' becomes 'u'.
'against' is a charade indicator (letters next to each other).
'piece' becomes 'bit' (bit is a kind of piece**).
'workers' becomes 'men' (man is a kind of worker).
'u' after 'bit' is 'bitu'.
'bitu'+'men'='BITUMEN'
(Other definitions for bitumen that I've seen before include "Tarry substance used to surface roads and roofs" , "Asphalt" , "coverage on the streets?" , "Road-surfacing material" , "Road's topping" .)