Raze building and tower (4,4)
I believe the answer is:
tear down
'raze' is the definition.
(synonyms)
'building and tower' is the wordplay.
'building' indicates anagramming the letters.
'and'+'tower'='andtower'
'andtower' anagrammed gives 'TEAR DOWN'.
(Other definitions for tear down that I've seen before include "Level" , "Demolish" , "trash" .)