Wary when left with spooky sound (5)
I believe the answer is:
leery
'wary' is the definition.
(thesaurus)
'left with spooky sound' is the wordplay.
'left' becomes 'l' (common abbreviation).
'with' is a charade indicator (letters next to each other).
'spooky' becomes 'eerie' ('eerie' can be a synonym of 'spooky').
'sound' indicates a 'sounds like' (homophone) clue.
'eerie' is a homophone of 'eery'.
'l'+'eery'='LEERY'
'when' is the link.
(Other definitions for leery that I've seen before include "Suspiciously cautious" , "In slang, wary or suspicious - reely!" , "Cautious due to suspicions" , "Sly, cunning" , "Shy" .)