Tell a secret (5,3,5)
(Other definitions for spill the beans that I've seen before include "Let the cat out of the bag" , "Give the game away" , "Reveal secret information" , "Blab" , "Embarrassingly reveal a secret" .)
'tell a secret' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tattle that I've seen before include "Chatter idly" , "Tell tales" , "Inform on someone" , "Divulge secrets" , "'Gossip, idle talk (6)'" .)