The most common and most likely answer to this crossword clue is the 8 letter word SPITTOON
I've seen this crossword clue in The Guardian
S
P
I
T
T
O
O
N
More clues leading to the result SPITTOON
- Old hacker's target presently, PM admitted
- One not drinking in old club: I may collect rejected wine
- Hawk's target before long includes PM
- Vessel that’s not long transporting PM
- This allowed pub customers to get stuff off their chest
- Hawking’s destination in the near future opened by former Prime Minister [Maggie]
- Bucket of “poison” thrown over abstainer
- Describing time travelling options, here’s Hawking
Buddy explains!

The straight part
We know that "This allowed pub customers to get stuff off their chest" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this allowed pub customers to get stuff off their chest = spittoon.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.
What does SPITTOON mean?
SPITTOON noun- A receptacle for spit.