One having a dozen donuts? That's a lot, even for Brits these days! (8)
I believe the answer is:
trillion
'one' is the definition.
The definition and answer can be both quantities as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'a dozen donuts? that's a lot even for brits these days' is the wordplay.
I cannot quite understand how this works, but
'lot' could be 'ill' (ill is a kind of lot) and 'ill' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'having' acts as a link.
Can you help me to learn more?
(Other definitions for trillion that I've seen before include "1,000,000,000,000" , "US billion" , "1 and 18 zeros" , "Very large power of 10" , "A great number" .)