Spies protect working-class syndicates (9)
I believe the answer is:
consortia
'syndicates' is the definition.
('consortium' can be a synonym of 'syndicate')
'spies protect working-class' is the wordplay.
'spies' becomes 'CIA' (Central Intelligence Agency).
'protect' is an insertion indicator.
'working' becomes 'on' (on can mean working or activated).
'class' becomes 'sort' (synonyms).
'on'+'sort'='onsort'
'cia' going around 'onsort' is 'CONSORTIA'.
(Other definitions for consortia that I've seen before include "Alliances" , "Groups of companies" , "More than one commercial group" , "firms" , "Groups of bodies" .)