Decline to cross current in front of building (6)
I believe the answer is:
facade
'front of building' is the definition.
(I've seen this before)
'decline to cross current' is the wordplay.
'decline' becomes 'fade' (fade can mean to die away or decline).
'to cross' indicates putting letters inside (some letters cross or go round others).
'current' becomes 'ac' (alternating current).
'fade' going around 'ac' is 'FACADE'.
'in' is the link.
(Other definitions for facade that I've seen before include "Outward appearance, may obscure reality" , "Front-of-house" , "Walton's setting of Sitwell's verses" , "Front presented" , "Walton's work" .)