To have property in backstreet built-up areas (5)
I believe the answer is:
towns
'built-up areas' is the definition.
'towns' can be an answer for 'areas' (town is a kind of area). I'm unsure of the 'built-up' bit.
'to have property in backstreet' is the wordplay.
'to have property' becomes 'own' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'backstreet' becomes 'ts' ('st' backwards).
'own' placed inside 'ts' is 'TOWNS'.
Can you help me to learn more?
(Other definitions for towns that I've seen before include "Settlements" , "Municipalities" , "Urban areas" , "Places" .)