Drink children fed to bird that perished (5)
I believe the answer is:
mocha
'drink' is the definition.
(mocha is a kind of drink)
'children fed to bird that perished' is the wordplay.
'children' becomes 'ch' (genealogical abbreviation).
'fed to' indicates putting letters inside.
'bird that perished' becomes 'moa' (extinct bird).
'ch' put inside 'moa' is 'MOCHA'.
(Other definitions for mocha that I've seen before include "Dark brown" , "Kind of coffee" , "Macho (anag.); coffee with chocolate" , "Kid" , "Coffee drink" .)