Government uses spin taking on Labour theory (9)
I believe the answer is:
guesswork
'theory' is the definition.
(thesaurus)
'government uses spin taking on labour' is the wordplay.
'government' becomes 'g' (abbreviation for government).
'spin' indicates an anagram.
'taking on' indicates putting letters inside.
'labour' becomes 'work' (I've seen this before).
'uses' anagrammed gives 'uess'.
'g' going inside 'uess' is 'guess'.
'guess'+'work'='GUESSWORK'
(Other definitions for guesswork that I've seen before include "Speculation" , "Supposition" , "Conjecture" , "Formation of opinion without definite knowledge" .)