Some extra illumination is required for the path (5)
I believe the answer is:
trail
'the path' is the definition.
(trail is a kind of path)
'some extra illumination is' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'TRAIL' can be found hidden inside 'extra illumination is'.
'required for' is the link.
(Other definitions for trail that I've seen before include "Beaten path; follow" , "Pursue" , "Get behind" , "Follow - track" , "Linger behind" .)