Detective's quest (4)
I believe the answer is:
clue
'detective's quest' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for clue that I've seen before include "It helps towards the solution" , "Hint; piece of evidence" , "Evidence that helps to solve a problem" , "Slight indication (as here)" , "Lead" .)