Thin wire or thread (8)
I believe the answer is:
filament
I believe this clue is a double definition.
'thin wire' is the first definition.
(I've seen this before)
'thread' is the second definition.
(I have seen 'Thin thread ' mean 'filament' so perhaps 'thread' could also mean 'filament')
(Other definitions for filament that I've seen before include "It glows in a light bulb" , "one can become incandescent" , "Wire in light bulb" , "Wire in incandescent bulb" , "Slender thread - conducting wire" .)