The most common and most likely answer to this crossword clue is the 4 letter word SIZE
I've seen this crossword clue in The Times
S
I
Z
E
More clues leading to the result SIZE
- Measure of what decorators use
- Mass complaints in radio broadcast
- Measure is indicating relief by the sound of it?
- Volume of glue
- Extent of heavy breathing on the phone
- Maybe volume that whispers are heard
- Volume of exhalations reported.
- Assess sad sounds
- Measure gluey material
- Volume of moans gently audible
Buddy explains!

The straight part
We know that "Volume" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case volume = size.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 SIZE mean?
SIZE noun- (obsolete outside dialectal) An assize.
- A regulation determining the amount of money paid in fees, taxes etc.
- A fixed standard for the magnitude, quality, quantity etc. of goods, especially food and drink.
- The dimensions or magnitude of a thing; how big something is.
- A regulation, piece of ordinance.
- A specific set of dimensions for a manufactured article, especially clothing.
- A number of edges in a graph.
- Degree of rank, ability, character, etc.
- An instrument consisting of a number of perforated gauges fastened together at one end by a rivet, used for measuring the size of pearls.
- To adjust the size of; to make a certain size.
- To classify or arrange by size.
- To approximate the dimensions, estimate the size of.
- To take a greater size; to increase in size.
- (Cambridge University) To order food or drink from the buttery; hence, to enter a score, as upon the buttery book.
- To swell; to increase the bulk of.
- A thin, weak glue used as primer for paper or canvas intended to be painted upon.
- Wallpaper paste.
- The thickened crust on coagulated blood.
- Any viscous substance, such as gilder's varnish.
- To apply glue or other primer to a surface which is to be painted.