It comes later to one in search of illumination (9)
I believe the answer is:
afterglow
'it comes later' is the definition.
The definition suggests a singular noun which matches the answer.
'one in search of illumination' is the wordplay.
'one in search of' becomes 'after' (I've seen this in another clue).
'illumination' becomes 'glow ' (I've seen this before).
'after'+'glow'='AFTERGLOW'
'to' is the link.
Can you help me to learn more?
(Other definitions for afterglow that I've seen before include "Light once the actual source has gone" , "Pleasure of remembering something nice" , "trace of sunset" , "Remaining light" , "Light in the sky post sunset" .)