Very cheerful, but in trouble here? (4)
I believe the answer is:
soup
'in trouble here?' is the definition.
('in the soup' means in trouble)
'very cheerful' is the wordplay.
'very' becomes 'so' (both can mean 'extremely').
'cheerful' becomes 'up' (I've seen this in other clues).
'so'+'up'='SOUP'
'but' acts as a link.
(Other definitions for soup that I've seen before include "Cock-a-leekie, for example" , "Eg, potage, broth" , "Preliminary course" , "Liquid - course" , "Stolen plate melted down" .)