The most common and most likely answer to this crossword clue is the 6 letter word HELIUM
I've seen this crossword clue in The Guardian
H
E
L
I
U
M
More clues leading to the result HELIUM
- Gas starts to inflate umpteen wheel surrounds
- Sing about high priest’s balloon content?
- He‘s a priest, surrounded by noise
- He gets a buzz touring French island northwards
- He
- Stink engulfing priest, gas!
- Lie about in stench producing gas
- He spread murmur about priest
- He needs leadership to suppress independent university?
Buddy explains!
The straight part
We know that "balloon content" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case balloon content = helium.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 HELIUM mean?
HELIUM noun- The second lightest chemical element (symbol He) with an atomic number of 2 and atomic weight of 4.002602, a colorless, odorless and inert noble gas.
- A form or sample of the element.