Popular one-time source of session singers (9)

I believe the answer is:

informers

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

'singers' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'popular one-time source of session' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'one-time' becomes 'former' (I've seen this in another clue).
'source of' indicates taking the first letters (the start - or source - of the word).
The first letter of 'session' is 's'.
'in'+'former'+'s'='INFORMERS'

Can you help me to learn more?

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app