"Calling" company (4)
I believe the answer is:
avon
'calling company' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for avon that I've seen before include "English river flowing through Stratford" , "River joining Bath with Bristol" , "Shakespeare is know as the Bard of . . . ." , "English river, flows through Stratford" , "River flowing through Bristol to the Severn" .)