Computer displayed academic credential? (9)

I believe the answer is:

mainframe

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

'computer' is the definition.
(mainframe computer is a kind of computer)

'displayed academic credential?' is the wordplay.
I cannot quite understand how this works, but
'academic' could be 'ma' and 'ma' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for mainframe that I've seen before include "Computer's central processing unit" , "Principal computer" , "Large central computer" , "Computer system" , "powerful computer" .)

I've seen this clue in The Times.

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