Beast of burden arrived at Leatherhead (5)
I believe the answer is:
camel
'beast of burden' is the definition.
(I've seen this before)
'arrived at leatherhead' is the wordplay.
'arrived' becomes 'came' (come can mean to appear or arrive).
'at' says to put letters next to each other.
'leatherhead' becomes 'l' (head letter of 'leather').
'came'+'l'='CAMEL'
(Other definitions for camel that I've seen before include "Old WWI plane" , "Humped ungulate" , "African transport" , "fawn" , "Humped animal" .)