With weight, he disputes it (6)
I believe the answer is:
denier
'with weight he disputes it' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'with weight he' is the wordplay.
I cannot quite understand how this works, but
'he' could be 'den' and 'den' is present in the answer.
The remaining letters 'ier' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for denier that I've seen before include "Measurement of fineness in silk, nylon etc" , "Conspiracist probably" , "Measure of the fineness of silk or nylon" , "One refusing to accept" , "Unit of weight for fine material, silk or nylon" .)