It's a job to cover the inside (4)
I believe the answer is:
line
This clue is a double definition.
'it's a job' is the first definition.
(line can mean someone's line of work)
'cover the inside' is the second definition.
(I've seen this in another clue)
'to' is the link.
(Other definitions for line that I've seen before include "Phone connection; queue" , "Wrinkle; phone link" , "Formation of one beside another" , "column" , "Ancestry" .)