Make attractive border prominent feature (6)
I believe the answer is:
endear
'make attractive' is the definition.
(synonyms)
'border prominent feature' is the wordplay.
'border' becomes 'end' (end can mean a border or edge).
'prominent feature' becomes 'ear' (facial feature).
'end'+'ear'='ENDEAR'
(Other definitions for endear that I've seen before include "Draw" , "Inspire affection" , "Arouse affection" , "ingratiate" , "Make fond" .)