Sweet — for instance doughy pudding — not finished up (5)
I believe the answer is:
fudge
'sweet' is the definition.
(I know that fudge is a sweet)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for fudge that I've seen before include "Equivocate - sweetmeat" , "Falsify - soft sweet" , "Soft creamy sweet" , "sugar, butter and cream" , "Something sweet" .)