Possible Clues:

• I received the news in confidence. Robin was my informant maybe? (1,6,4,4,2)
• I heard it from an unspecified source (1,6,4,4,2)
• I heard it from a source I won't reveal (1,6,4,4,2)
• Dr Dolittle able, especially, with it to retain mystery initially? (1,6,4,4,2)