The most common and most likely answer to this crossword clue is the 5 plus 4 letter word INNER TUBE
I've seen this crossword clue in Financial Times
I
N
N
E
R
T
U
B
E
More clues leading to the result INNER TUBE
- Trendy new bath filling before getting inflatable ring
- Bike part from Benin? True, surprisingly
- Crossing Tiber with nun, cardinal produces rubber ring
- Item pumped full of air, entire bun exploding!
- Number taken in by sluggish university — happen it should be blown up
- Means of getting around central London, perhaps essential for cyclists under pressure?
- Wheel lining beer tun in development
- Wind turbine harnessing nuclear energy? It should be blown up!
Buddy explains!
The straight part
We know that "Item pumped full of air" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case item pumped full of air = inner tube.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.