Slick-talking (4)
I believe the answer is:
glib
'slick-talking' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for glib that I've seen before include "Insincerely fluent" , "Fluent but evasive" , "Smooth-talking" , "Silver-tongued" , "Fluent but insincere" .)