Small piece of food (6)
(Other definitions for titbit that I've seen before include "Pleasing scrap of gossip" , "Choice bit of something, food or gossip" , "Small piece of tasty food" , "Dainty morsel" , "Delicacy" .)
(Other definitions for crumb that I've seen before include "Very little comfort perhaps" , "Very small quantity of something, especially food" , "A tiny bit of bread" , "Small bit (of comfort?)" , "Just a little bit" .)