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 see how this works, but
'he' could be 'den' and 'den' is located in the answer.
The remaining letters 'ier' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
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" .)