A close friend's hint (8)
I believe the answer is:
intimate
This clue is a double definition.
'a close friend's' is the first definition.
(thesaurus)
'hint' is the second definition.
(intimating is a kind of hinting)
(Other definitions for intimate that I've seen before include "Tip off" , "Familiar; imply" , "Hint to a familiar friend" , "Sharing a close and affectionate friendship" , "Suggest to trusted friend?" .)