Fluent and plausible (4)
I believe the answer is:
glib
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fluent and plausible</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for glib that I've seen before include "Fluent but evasive" , "Of speech, facile but insincere" , "Slippery in speech" , "Fluent but insincere" , "Having only superficial plausibility" .)