Old playful spooks rising up (7)
I believe the answer is:
archaic
'old' is the definition.
(similar in meaning)
'playful spooks rising up' is the wordplay.
'playful' becomes 'arch' (I've seen this before).
'spooks' becomes 'CIA' (spooks can mean spies).
'rising up' shows that the letters should be reversed in order (in a down clue, letters go up).
'cia' in reverse letter order is 'aic'.
'arch'+'aic'='ARCHAIC'
(Other definitions for archaic that I've seen before include "A long way out of date" , "Antiquated" , "Very old or old-fashioned" , "Belonging to former times like some words" , "Ancient or out of date" .)