School was concealing singular vague sound (5)

I believe the answer is:

schwa

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

'vague sound' is the definition.
'schwa' can be an answer for 'sound' (schwa is a kind of sound). I am not sure about the 'vague' bit.

'school was concealing singular' is the wordplay.
'school' becomes 'sch' (common abbreviation).
'concealing' is a deletion indicator.
'singular' becomes 's' (abbreviation sometimes used in dictionaries).
'was' with 's' taken away is 'wa'.
'sch'+'wa'='SCHWA'

Can you help me to learn more?

(Other definitions for schwa that I've seen before include "Unstressed vowel (phonetics)" , "Uh' sound" , "Indistinct sound" , "sound unstressed" , "Stress-free sound" .)

I've seen this clue in The Times.

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.