Choice to limit time working (9)
I believe the answer is:
operation
'working' is the definition.
(thesaurus)
'choice to limit time' is the wordplay.
'choice' becomes 'option' ('option' can be a synonym of 'choice'**).
'to limit' is an insertion indicator.
'time' becomes 'era' (I've seen this before).
'option' enclosing 'era' is 'OPERATION'.
(Other definitions for operation that I've seen before include "battle" , "working" , "military undertaking" , "To one pair (anag.)" , "Surgical or military piece of work" .)