Ruins hiding English horses (5)

I believe the answer is:

mares

'horses' is the definition.
(mare is a kind of horse)

'ruins hiding english' is the wordplay.
'ruins' becomes 'mars' (I've seen this before).
'hiding' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'mars' placed around 'e' is 'MARES'.

(Another definition for mares that I've seen is " Female horses".)

I've seen this clue in The Mirror.

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