The most common and most likely answer to this crossword clue is the 7 letter word BULBOUS
I've seen this crossword clue in Financial Times
B
U
L
B
O
U
S
More clues leading to the result BULBOUS
Buddy explains!

The straight part
We know that "Swollen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case swollen = bulbous.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 BULBOUS mean?
BULBOUS adjective- Having the shape of or resembling a bulb, bloated.
- (of a person) Overweight and round in shape.
- Growing from a bulb or producing bulbs.