Letter sent to performers indicating that they wouldn't be playing leading roles (9,6)

I believe the answer is:

character actors

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

'performers indicating that they wouldn't be playing leading roles' is the definition.
'character actors' can be an answer for 'performers' (character actor is a kind of performer). I am not sure about the rest of the definition.

'letter sent' is the wordplay.
'letter' becomes 'character' (written character).
'sent' becomes 'actors' (I am not sure about this - if you are sure you should believe this answer much more).
'character'+'actors'='CHARACTER ACTORS'

'to' acts as a link.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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