One glib, slippery — of low character (7)
I believe the answer is:
ignoble
'of low character' is the definition.
(I've seen this in another clue)
'one glib slippery' is the wordplay.
'slippery' indicates anagramming the letters (I've seen this in other clues).
'one'+'glib'='oneglib'
'oneglib' anagrammed gives 'IGNOBLE'.
(Other definitions for ignoble that I've seen before include "Inferior" , "Base - in globe (anag)" , "Not honourable in character or purpose" , "'Base, dishonourable (7)'" , "'Far from the madding crowd's . . . . . . . strife'" .)