Greek agents about to acquire Times (5)
I believe the answer is:
attic
'greek' is the definition.
(from ancient Athens or Attica)
'agents about to acquire times' is the wordplay.
'agents' becomes 'CIA' (Central Intelligence Agency).
'about' shows that the letters should be reversed in order.
'to acquire' indicates putting letters inside.
'times' becomes 'tt' (an abbreviation for time written twice).
'cia' in reverse letter order is 'aic'.
'aic' enclosing 'tt' is 'ATTIC'.
(Other definitions for attic that I've seen before include "The highest room" , "Athenian Greek" , "Ancient Greek; loft" , "Classically elegant" , "Upper chamber" .)