Stands across most excellent mounts (9)

I believe the answer is:

bestrides

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'stands across' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot see how they can define each other.

'most excellent mounts' is the wordplay.
'most excellent' becomes 'best' (the very best).
'mounts' becomes 'rides' ('ride' can be a synonym of 'mount').
'best'+'rides'='BESTRIDES'

Can you help me to learn more?

(Other definitions for bestrides that I've seen before include "Steps across" , "dominates" .)

I've seen this clue in the Sydney Morning Herald.

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