Stormy until dark (5)
I believe the answer is:
unlit
'dark' is the definition.
(similar in meaning)
'stormy until' is the wordplay.
'stormy' is an anagram indicator.
'until' anagrammed gives 'UNLIT'.
(Other definitions for unlit that I've seen before include "Not illuminated" , "Not yet fired up" , "dim" , "Left in the dark" , "Not yet burning" .)