Fluent (4)
'fluent' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for voluble that I've seen before include "Given to talking a lot" , "Gabby, garrulous" , "Talking a lot, overly fluent" , "With plenty to say" , "Loquacious" .)
'fluent' 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" , "Only superficially plausible" , "Silver-tongued" , "freedom of speech?" , "Ready with insincere or superficial words" .)