Swiftlet regularly seen on this place (4)
I believe the answer is:
site
'this place' is the definition.
(site is a kind of place)
'swiftlet regularly seen' is the wordplay.
'regularly seen' means one should take alternating letters.
The alternate letters of 'swiftlet' are 'SITE'.
'on' is the link.
(Other definitions for site that I've seen before include "Locate - place" , "Locate, position" , "Building plot" , "Ties into building location" , "Building land" .)