Tattler (12)
'tattler' is the definition.
(I know that tattler can be written as telltale)
This is all the clue.
(Other definitions for telltale that I've seen before include "Monitoring device - gossip" , "Revealing or indicating something, like blabbermouth" , "Gossip-monger" , "Betraying" , "Revealer of secrets" .)
'tattler' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for blabbermouth that I've seen before include "Indiscreet talker" , "Indiscreet individual - humbler abbot (anag)" , "Gossiper" , "Person who talks indiscreetly" , "Person who gossips all the time" .)