The most common and most likely answer to this crossword clue is the 6 letter word DOWNED
I've seen this crossword clue in The Times
D
O
W
N
E
D
Buddy explains!
The straight part
We know that "swallowed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case swallowed = downed.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 DOWNED mean?
DOWNED verb- To knock (someone or something) down; to cause to come down, to fell.
- To lower; to put (something) down.
- To defeat; to overpower.
- To disparage, to put down.
- To go or come down; to descend.
- To drink or swallow, especially without stopping before the vessel containing the liquid is empty.
- To render (the ball) dead, typically by touching the ground while in possession.
- (pocket billiards) To sink (a ball) into a hole or pocket.
- To cover, ornament, line, or stuff with down.
- That has been brought down.