Slight; elusive (6)
I believe the answer is:
subtle
This clue is a double definition.
'slight' is the first definition.
(I've seen this before)
'elusive' is the second definition.
(I know that elusive can be written as subtle)
(Other definitions for subtle that I've seen before include "Tenuous; refined" , "Slight and difficult to analyse amid bustle" , "Not blatant" , "Understated; devious" , "Very nice" .)