Singer causing surprise with split from Heart (8)
I believe the answer is:
'singer' is the definition.
(starling is a kind of birdanimal)
'surprise with split from heart' is the wordplay.
I cannot really see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is found within the answer.
This explanation may well be incorrect...
'causing' is the link.
Can you help me to learn more?
(Other definitions for starling that I've seen before include "Passerine bird" , "Stellar bird with blackish speckled feathers" , "is naturally a good mimic" , "Dark, glossy bird" , "Might Gran list badly for the bird" .)