British declared regret for cuppa (4)
I believe the answer is:
brew
'cuppa' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'british declared regret' is the wordplay.
'british' becomes 'br' (abbreviation for British).
'declared regret' becomes 'ew' (I am not sure about this - if you are sure you should believe this answer much more).
'br'+'ew'='BREW'
'for' is the link.
Can you help me to learn more?
(Other definitions for brew that I've seen before include "A pot of tea?" , "Cup of tea (informal)" , "Mixture" , "Infuse" , "Steep" .)