Snitch giving this sign? (8)
I believe the answer is:
telltale
This clue is a double definition.
'snitch' is the first definition.
(thesaurus)
'this sign?' is the second definition.
(thesaurus)
'giving' is the link.
(Other definitions for telltale that I've seen before include "Revealer of secrets" , "Revealing indicator or sneak" , "Person who blabs or something that reveals" , "Blabber-mouth, can't keep a secret" , "One spreads other people's secrets" .)