Goes spearing, we're told, in hellish river (4)
I believe the answer is:
styx
'hellish river' is the definition.
(I've seen this in another clue)
'goes spearing we're told' is the wordplay.
'goes spearing' becomes 'sticks'.
'we're told' indicates a 'sounds like' (homophone) clue.
'sticks' is a homophone of 'STYX'.
'in' acts as a link.
(Other definitions for styx that I've seen before include "One of the rivers of Hades" , "River of hell" , "River separating Earth from Hades" , "Charon's 26 carried dead souls across this river" , "Hellish current" .)