Page including surplus material (7)
I believe the answer is:
padding
'surplus material' 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?
'page including' is the wordplay.
I cannot really understand how this works, but
'page' could be 'p' and 'p' is found in the answer.
The remaining letters 'adding' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for padding that I've seen is " Soft stuffing".)