Aspired to become an excellent medium (5)

I believe the answer is:

aimed

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'aspired' is the definition.
('aim' can be a synonym of 'aspire')

'an excellent medium' is the wordplay.
'an excellent' becomes 'ai'.
'medium' becomes 'med' (I can't justify this - if you can you should give a lot more credence to this answer).
'ai'+'med'='AIMED'

'to become' is the link.

Can you help me to learn more?

(Other definitions for aimed that I've seen before include "Focused on as target" , "Directed, targeted" , "Set sights on for a dime" , "Directed towards specified goal" , "Planned, intended to try" .)

I've seen this clue in the Evening Standard.

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