Intrusion, once merchant moved out (12)
I believe the answer is:
encroachment
'intrusion' is the definition.
(synonyms)
'once merchant moved out' is the wordplay.
'once merchant' can be anagrammed to 'ENCROACHMENT'.
However, I am not sure how this is indicated.
Can you help me to learn more?
(Other definitions for encroachment that I've seen before include "Gradual intrusion" , "An advance beyond expected limits" .)