This person's architectural feature creates an obstruction (10)
I believe the answer is:
impediment
'an obstruction' is the definition.
('impediment' can be a synonym of 'obstruction')
'this person's architectural feature' is the wordplay.
'this person's' becomes 'im' (this person means the crossword setter themselves).
'architectural feature' becomes 'pediment' (I've seen this before).
'im'+'pediment'='IMPEDIMENT'
'creates' acts as a link.
(Other definitions for impediment that I've seen before include "Obstacle" , "Let" , "Hindrance, obstruction" , "opposition" .)