Drive past houses vacated - but they can be plumbed (6)
I believe the answer is:
depths
'they can be plumbed' is the definition.
The definition suggests an adverb but the answer is not.
'drive past houses vacated' is the wordplay.
'drive past' becomes 'dept' (I can't justify this - if you can you should give a lot more credence to this answer).
'vacated' suggests removing the centre (internal letters vacate the word).
'houses' with its centre removed is 'hs'.
'dept'+'hs'='DEPTHS'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for depths that I've seen before include "Sea bottom" , "Distances down or front to back" , "lowest part" , "obscurities" , "Extents downward, backward or inward" .)