Unexpected ingredient in this pudding (4)
I believe the answer is:
spud
'unexpected ingredient' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'in this pudding' is the wordplay.
'in' says the answer is hidden in the clue.
'SPUD' is hidden within 'this pudding'.
Can you help me to learn more?
(Other definitions for spud that I've seen before include "short, stocky person" , "Weed spade" , "Spade; potato (slang)" , "Charlotte perhaps" , "King Edward, say (slang)" .)