We get tough with a horse opera (7)

I believe the answer is:

western

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'a horse opera' is the definition.
('Western' can be a synonym of 'horse opera')

'we get tough' is the wordplay.
'get tough' becomes 'stern' (I can't justify this - if you can you should give a lot more credence to this answer).
'we'+'stern'='WESTERN'

'with' is the link.

Can you help me to learn more?

(Other definitions for western that I've seen before include "Cowboys and Indians movie" , "Spaghetti film?" , "The Occident" , "American film" , "Type of film or music" .)

I've seen this clue in the Evening Standard.

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