Beetle (6)
There are a few possibilities for this:
glow-worm
'beetle' is the definition.
(scarab is a kind of beetle)
This is all the clue.
(Other definitions for scarab that I've seen before include "Egyptian stone" , "Beetle revered in ancient Egypt" , "Sacred Eygptian beetle" , "Beetle revered by ancient Egyptians" , "Beetle regarded as divine by ancient Egyptians" .)
(Other definitions for weevil that I've seen before include "Beetle, a grain pest" , "Small beetle, crop pest" , "Type of beetle that feeds of stored grain etc" , "Evil we find strangely in a beetle" , "Destructive beetle" .)
'beetle' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for glow-worm that I've seen before include "Kind of beetles that emit greenish light" , "Beetle whose larva-like wingless females emit light" , "Beetle whose female bears luminescent green organs" , "Beetle whose wingless females are partly luminous" , "Shining beetle" .)