Root (out) (4)
'root out' is the definition.
(root out can mean to eradicate or remove)
This is the entire clue.
(Other definitions for eradicate that I've seen before include "Excise" , "Expunge" , "scratch" , "Destroy completely" , "Scotch" .)
(Other definitions for suss that I've seen before include "Divine nature of" , "Realise (informal)" , "Work (out) (slang)" , "Figure (out)" , "Discover (slang)" .)