Conceal the part of the house that's ugly (7)
I believe the answer is:
hideous
'ugly' is the definition.
(similar in meaning)
'conceal the part of the house' is the wordplay.
'conceal' becomes 'hide' (synonyms).
'the part of the house' becomes 'ous' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'hide'+'ous'='HIDEOUS'
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for hideous that I've seen before include "Repulsive" , "Horrible" , "revolting" , "Ghastly" , "Extremely ugly" .)