Letters provided by classics teachers maybe after school (6)

I believe the answer is:

gammas

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

'letters' is the definition.
(gamma is a kind of letter)

'maybe after school' is the wordplay.
'maybe' becomes 'mas' (I am not sure about this - if you are sure you should believe this answer much more).
'after' is a charade indicator (letters next to each other).
'school' becomes 'gam' (I've seen this in other clues).
'mas' put after 'gam' is 'GAMMAS'.

'provided by classics teachers' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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.