Place it within the borders of Singapore (4)
I believe the answer is:
site
'place' is the definition.
(site is a kind of place)
'it within the borders of singapore' is the wordplay.
'within' indicates putting letters inside.
'the borders of' means to remove the middle letters.
'singapore' with its centre taken out is 'se'.
'it' inserted into 'se' is 'SITE'.
(Other definitions for site that I've seen before include "Locality" , "Position; situation" , "Locale" , "Whereabouts" , "Web location; place" .)