Somewhat damp, ref abandons building (6)
I believe the answer is:
prefab
'building' is the definition.
(I have seen 'Temporary building ' mean 'prefab' so perhaps 'building' could also mean 'prefab')
'somewhat damp ref abandons' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'PREFAB' can be found hidden inside 'damp ref abandons'.
(Other definitions for prefab that I've seen before include "Type of house" , "home -- temporary one?" , "Building constructed in advance of its erection" , "British inter-war temporary housing, popularly called" , "Building assembled on site" .)