Many sketches needing no introduction (6)
I believe the answer is:
oodles
'many' is the definition.
(I've seen this before)
'sketches needing no introduction' is the wordplay.
'sketches' becomes 'doodles' (I've seen this before).
'needing no introduction' means to remove the first letter.
'doodles' with its initial letter taken away is 'OODLES'.
(Other definitions for oodles that I've seen before include "Large number or amount" , "wealth" , "Tons, scads" , "A great many" , "Lots (colloq.)" .)