Ring for seats here in the theatre (6)
I believe the answer is:
circle
This clue is a double definition.
'ring' is the first definition.
(synonyms)
'seats here in the theatre' is the second definition.
(part of a theatre)
'for' is the link.
(Other definitions for circle that I've seen before include "Geometric shape" , "Upper theatre seating" , "Closed plane curve" , "Seats above theatre stalls" , "Round shape" .)