Prevent rebuilding above it (7)
I believe the answer is:
obviate
'prevent' is the definition.
(I know that obviate is a more specific form of the action prevent)
'rebuilding above it' is the wordplay.
'rebuilding' is an anagram indicator.
'above'+'it'='aboveit'
'aboveit' with letters rearranged gives 'OBVIATE'.
(Other definitions for obviate that I've seen before include "Avoid, prevent" , "Get round or do away with" , "Make unnecessary" , "Forestall" , "Anticipate" .)