Farm subdivision is a non-starter (5)
I believe the answer is:
ranch
'farm' is the definition.
(I know that ranch is a type of farm)
'subdivision is a non-starter' is the wordplay.
'subdivision' becomes 'branch' (synonyms).
'is a non-starter' means to remove the first letter (the letter which starts the word is ignored).
'branch' with its initial letter taken off is 'RANCH'.
(Other definitions for ranch that I've seen before include "Cattle-breeding farm in America, say in Texas" , "Run a cattle farm" , "A large cattle-breeding farm" , "Agricultural establishment" , "US establishment for livestock" .)