Mountain concealed at home for convenience (6)
I believe the answer is:
urinal
'for convenience' is the definition.
(I've seen this before)
'mountain concealed at home' is the wordplay.
'mountain' becomes 'ural' (I can't justify this - if you can you should give a lot more credence to this answer).
'concealed' is an insertion indicator.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'ural' enclosing 'in' is 'URINAL'.
Can you help me to learn more?
(Other definitions for urinal that I've seen before include "public convenience" , "Sanitary fitting" , "waste disposal unit" .)