Light resin (5)
I believe the answer is:
amber
I believe this is a double definition.
'light' is the first definition.
(I've seen this before)
'resin' is the second definition.
(amber is a type of resin)
(Other definitions for amber that I've seen before include "forever written about" , "Fossil resin - bream (anag)" , "Fossil resin - warning light" , "Yellowish translucent fossil resin" , "Fossil resin used in jewellery" .)