Right, the snake has a grating sound (4)
I believe the answer is:
rasp
'a grating sound' is the definition.
(I've seen this in another clue)
'right the snake' is the wordplay.
'right' becomes 'r' (common abbreviation).
'the snake' becomes 'asp' (asp is a kind of snake).
'r'+'asp'='RASP'
'has' acts as a link.
(Other definitions for rasp that I've seen before include "Make a grating noise" , "Harsh noise - file" , "It is used to grate" , "unpleasant noise" , "Grate; scrape" .)