A key opens outside door entering the house (5)
I believe the answer is:
abode
'the house' is the definition.
(I've seen this before)
'a key opens outside door entering' is the wordplay.
'key' becomes 'd' (I've seen this in other clues).
'opens' indicates putting letters inside (one set of letters makes an 'opening' in another).
'outside door entering' becomes 'boe' (I can't justify this - if you can you should give a lot more credence to this answer).
'd' put inside 'boe' is 'bode'.
'a'+'bode'='ABODE'
Can you help me to learn more?
(Other definitions for abode that I've seen before include "Archaic dwelling place" , "House, home" , "Where one lives" , "House made of adobe" , "Dwelling, residence" .)