24 across
Best
in
everything
for
big
Brits
(3,3,2,3,4)
Best in everything for big Brits (3,3,2,3,4)
hints
0
checks
0
hints
The whole clue is the definition (& lit or double definition).
How the clue works
Look at Best in everything — that's your first definition, pointing to the idiom "living off the fat of the land," meaning enjoying the best of everything. Then the setter's been cheeky with big Brits as a second, whimsical definition, reading it dead literally as "the fat (big people) of the land (Britain)."