One refusing to buy anything (7)
I believe the answer is:
sceptic
'one refusing to buy anything' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
(Other definitions for sceptic that I've seen before include "Disbeliever" , "I may doubt that" , "One who doubts accepted opinions" , "One questioning accepted opinions" , "Person who tends to disbelieve" .)