The most common and most likely answer to this crossword clue is the 3 plus 3 plus 3 plus 3 letter word ONE FOR THE POT
I've seen this crossword clue in The Daily Telegraph
O
N
E
F
O
R
T
H
E
P
O
T
Buddy explains!
The straight part
We know that "What a tea drinker often says/a farce" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what a tea drinker often says/a farce = one for the pot.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.