Lets art building with alarm (7)
I believe the answer is:
startle
'alarm' is the definition.
(I've seen this before)
'lets art building' is the wordplay.
'building' indicates anagramming the letters.
'lets'+'art'='letsart'
'letsart' is an anagram of 'STARTLE'.
'with' is the link.
(Other definitions for startle that I've seen before include "Surprise greatly, alarm" , "Shock, alarm" , "Frighten suddenly" , "Shock (someone)" , "Scare" .)