Big cat circles old feline site (8)
I believe the answer is:
location
'site' is the definition.
(thesaurus)
'big cat circles old feline' is the wordplay.
'big cat' becomes 'lion' (lion is a kind of big cat).
'circles' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'feline' becomes 'cat' (I've seen this before).
'o'+'cat'='ocat'
'lion' enclosing 'ocat' is 'LOCATION'.
(Other definitions for location that I've seen before include "Position, point in space" , "Position,place" , "Position or situation" , "Site of film production away from studio" , "Place, position" .)