Where birds breed round New Yorker circles (7)
I believe the answer is:
rookery
'where birds breed' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'round new yorker circles' is the wordplay.
'round' becomes 'o' (round can mean a round object).
'new' indicates anagramming the letters.
'circles' means one lot of letters goes inside another.
'yorker' is an anagram of 'rokery'.
'o' inserted within 'rokery' is 'ROOKERY'.
Can you help me to learn more?
(Other definitions for rookery that I've seen before include "Lofty breeding-place" , "Breeding-place of birds, penguins, seals" , "Breeding colony of birds, also of seals or turtles" , "Colony of penguins or seals" , "Noisy bird colony" .)