A second-rate dyer, one avoiding the hard stuff (9)
I believe the answer is:
abstainer
'one avoiding the hard stuff' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'a second-rate dyer' is the wordplay.
'second rate' becomes 'b'.
'dyer' becomes 'stainer' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a'+'b'+'stainer'='ABSTAINER'
Can you help me to learn more?
(Other definitions for abstainer that I've seen before include "Rechabite" , "One refusing hard stuff" , "Band of Hope member" , "Teetotaller" , "Bull's not my stuff" .)