Cask of tea before upturned tub (4)
I believe the answer is:
butt
'cask' is the definition.
(I know that butt is a type of cask)
'tea before upturned tub' is the wordplay.
I cannot really understand how this works, but
'tea' could be 't' (I've seen this in other clues) and 't' is found within the answer.
an anagram of 'tub' is 'but' which is within the answer.
No letters remain.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for butt that I've seen before include "Object of scorn, of humour" , "Fag-end" , ""bottom" to US" , "Hit with the head; object of ridicule" , "What goat may do" .)