Useless; pudding (4)
I believe the answer is:
duff
I believe this is a double definition.
'useless' is the first definition.
(I've seen this before)
'pudding' is the second definition.
(I know that Duff is a type of pudding)
(Other definitions for duff that I've seen before include "Worthless; pudding" , "False; steamed pudding" , "Faulty (slang); a pudding" , "Steamed pudding - 2" , "Heavy pudding - no good" .)