Douglas here maintains svelte physique eating zero fat meals primarily (4,2,3)
I believe the answer is:
isle of man
'douglas here maintains svelte physique eating zero fat meals primarily' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
Can you help me to learn more?
(Other definitions for isle of man that I've seen before include "Its cats are said to be lacking tails" , "Island in the Irish Sea" , "Island in 33 Across where cats have no tails" , "'It's in the Irish Sea (4,2,3)'" , "tax haven" .)