Bird died in flock (5)
I believe the answer is:
crowd
'flock' is the definition.
(I've seen this before)
'bird died' is the wordplay.
'bird' becomes 'crow' (crow is a kind of bird).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'crow'+'d'='CROWD'
'in' is the link.
(Other definitions for crowd that I've seen before include "assembly" , "Masses" , "Army" , "Throng" , "Social set" .)