Hint needed in a knotty situation? The opposite (8)
I believe the answer is:
antipode
'opposite' is the definition.
(thesaurus)
'hint needed in a knotty situation?' is the wordplay.
'hint' becomes 'tip' (synonyms).
'needed in' means one lot of letters goes inside another.
'knotty situation?' becomes 'node' (node can mean a knotty lump).
'a'+'node'='anode'
'tip' put inside 'anode' is 'ANTIPODE'.
'the' acts as a link.
(Other definitions for antipode that I've seen before include "Notepad I use to describe something diametrically opposite - Australia?" , "exact opposite" .)