A beast arrived late initially (5)
I believe the answer is:
camel
'a beast' is the definition.
(type of animal)
'arrived late initially' is the wordplay.
'arrived' becomes 'came' (come can mean to appear or arrive).
'initially' indicates taking the first letters.
The first letter of 'late' is 'l'.
'came'+'l'='CAMEL'
(Other definitions for camel that I've seen before include "African transport" , "Humped creature" , "Old WWI plane" , "Cud-chewing mammal of desert regions" , "Saddle animal in desert regions" .)