Rep demolished amazing house (6)
I believe the answer is:
'house' is the definition.
(I have seen 'Temporary house ' mean 'prefab' so perhaps 'house' could also mean 'prefab')
'rep demolished amazing' is the wordplay.
'demolished' is an anagram indicator.
'amazing' becomes 'fab' (I am not sure about this - if you are sure you should believe this answer much more).
'rep' with letters rearranged gives 'pre'.
Can you help me to learn more?
(Other definitions for prefab that I've seen before include "British inter-war temporary housing, popularly called" , "House assembled from parts" , "Easily-erected house" , "Building assembled from prepared parts" , "small postwar house" .)