I’m British in New York — I oppose local development (5)
I believe the answer is:
nimby
'i oppose local development' is the definition.
(short for 'not in my backyard')
'i'm british in new york' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'in' indicates putting letters inside.
'new york' becomes 'ny'.
'im'+'b'='imb'
'imb' inserted within 'ny' is 'NIMBY'.
(Other definitions for nimby that I've seen before include "Self-interested objector to local development" , "One not wanting local development (colloq.)" , "One wanting to protect area" , "'Not in my backyard' (abbrev.)" , "person guarding his immediate environment" .)