Distribution of lather is concealing variable result of salon treatment (9)

I believe the answer is:

hairstyle

I'm a little stuck... Click here to teach me more about this clue!

'treatment' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for hairstyle that I've seen before include "Design of crowning glory" , "Pageboy or bob, say" , "DA possibly" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.