Real solid houses to boot (4)
I believe the answer is:
also
'to boot' is the definition.
(I've seen this before)
'real solid houses' is the wordplay.
'houses' indicates a hidden word (part of the clue houses the answer).
'ALSO' can be found hidden inside 'real solid'.
(Other definitions for also that I've seen before include "on top" , "an indication of more to come" , "As well, in addition" , "Item" , "revolutionary a part for Yugoslavia" .)