Ring any number in district (5)
I believe the answer is:
arena
'ring' is the definition.
(thesaurus)
'any number in district' is the wordplay.
'any number' becomes 'n' (I've seen this in other clues).
'in' is an insertion indicator.
'district' becomes 'area' (I've seen this before).
'n' going inside 'area' is 'ARENA'.
(Other definitions for arena that I've seen before include "Olympic venue?" , "Where gladiators fought" , "bowl? Possibly" , "Central area in sports stadium" , "dramatic situation" .)