Erect or demolish, we hear (5)
I believe the answer is:
raise
'erect' is the definition.
(I know that erect is a more specific form of the action raise)
'demolish we hear' is the wordplay.
'demolish' becomes 'raze' (I've seen this before).
'we hear' indicates a 'sounds like' (homophone) clue.
'raze' is a homophone of 'RAISE'.
'or' is the link.
(Other definitions for raise that I've seen before include "To promote" , "Bring up, rear" , "climb" , "Lift; (to) levy (money)" , "Bring up a salary increase" .)