Horribly mendacious duo scorned entertainment venues (7)

I believe the answer is:

cinemas

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'horribly mendacious duo scorned' is the definition.
I can't tell whether this defines the answer.

'entertainment venues' is the wordplay.
'entertainment' becomes 'cinema' (I've seen this before).
'venues' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'cinema'+'s'='CINEMAS'

Can you help me to learn more?

(Other definitions for cinemas that I've seen before include "Picture-houses" , "Where films are shown" .)

I've seen this clue in The Irish Times.

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