The ambassador takes a minute on the border (3)
I believe the answer is:
hem
'the border' is the definition.
(I've seen this before)
'the ambassador takes a minute' is the wordplay.
'the ambassador' becomes 'he' (His or Her Excellency).
'takes' means one lot of letters go next to another.
'a minute' becomes 'm' (abbreviation).
'he'+'m'='HEM'
'on' acts as a link.
(Other definitions for hem that I've seen before include "Express hesitation" , "Sewn border" , "Double-backed edge" , "Bottom of a garment" , "Stitched edge of garment" .)