Yellow peril indicator (6)
I believe the answer is:
canary
This clue is a double definition.
'yellow' is the first definition.
(I know that canary is a type of yellow)
'peril indicator' is the second definition.
(as in a canary in a mine)
(Other definitions for canary that I've seen before include "Type of finch" , "Caged song bird" , "grass" , "Bright yellow bird" , "a sort of finch" .)