Opposed to substantial houses (4)

I believe the answer is:

anti

'opposed to' is the definition.
(I've seen this before)

'substantial houses' is the wordplay.
'houses' indicates a hidden word (part of the clue houses the answer).
'ANTI' can be found hidden inside 'substantial'.

(Other definitions for anti that I've seen before include "Naysayer" , "Not favouring" , "An opponent - opposed to party policy, etc" , "'No' voter" , "(Person who is) not in favour" .)

I've seen this clue in The Telegraph.

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