Durable, small buildings where horses are kept (7)
I believe the answer is:
stables
'durable small buildings' is the definition.
'stables' can be an answer for 'buildings' (stable is a kind of building). I am not certain of the 'durable small' bit.
'horses are kept' is the wordplay.
'horses' becomes 'stable' (I've seen this before).
'are kept' becomes 's' (I can't explain this - if you can you should believe this answer much more).
'stable'+'s'='STABLES'
'where' is the link.
Can you help me to learn more?
(Other definitions for stables that I've seen before include "Stalls for horses" , "Places where horses are kept" , "beastly residence" , "Where Arabs may be" , "Equine establishments" .)