Work placement hostility (10)
I believe the answer is:
opposition
'hostility' is the definition.
(thesaurus)
'work placement' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'placement' becomes 'position' (synonyms).
'op'+'position'='OPPOSITION'
(Other definitions for opposition that I've seen before include "parliamentary group" , "obstruction" , "those out of power" , "Rivalry" , "antagonism" .)