Backyard adjoining unpleasant house (7)
I believe the answer is:
dynasty
'house' is the definition.
(I've seen this before)
'backyard adjoining unpleasant' is the wordplay.
'backyard' becomes 'dy' (I can't justify this - if you can you should give a lot more credence to this answer).
'adjoining' says to put letters next to each other.
'unpleasant' becomes 'nasty' (nasty can mean unpleasant or horrible).
'dy'+'nasty'='DYNASTY'
Can you help me to learn more?
(Other definitions for dynasty that I've seen before include "Power line" , "Succession of relatives" , "TV series" , "Line of hereditary rulers" , "Song, say" .)