Job in street by river (4)
I believe the answer is:
post
'job' is the definition.
(post is a kind of job)
'street by river' is the wordplay.
'street' becomes 'st' (abbreviation).
'by' means one lot of letters go next to another.
'river' becomes 'Po' (Italian river).
'st' after 'po' is 'POST'.
'in' is the link.
(Other definitions for post that I've seen before include "trading establishment" , "Member < to comment on website" , "Upright - letters" , "Stake, job or mail" , "Publish' mail' job" .)