More than merely checked (5)

I believe the answer is:

mated

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'merely checked' is the definition.
Although both the answer and definition are past participle verbs, I cannot understand how they can define each other.

'more than' is the wordplay.
'more' becomes 'm'.
'than' becomes 'ated' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'm'+'ated'='MATED'

Can you help me to learn more?

(Other definitions for mated that I've seen before include "given match" , "Defeated in game" , "Joined, connected" , "had sex" .)

I've seen this clue in the Evening Standard.

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