Skinny and without teeth, what's-his-name? (9)
I believe the answer is:
thingummy
'what's-his-name?' is the definition.
(both may be used in place of a forgotten name)
'skinny and without teeth' is the wordplay.
'skinny' becomes 'thin' (similar in meaning).
'and' is a charade indicator (letters next to each other).
'without teeth' becomes 'gummy' (showing gums).
'thin'+'gummy'='THINGUMMY'
(Other definitions for thingummy that I've seen before include "whose name one's forgotten" , "unknown object" , "Unidentified object" , "what's-its-name" , "Oojamaflip" .)