He delivers upright staff (7)
I believe the answer is:
postman
'he delivers' is the definition.
(a postman delivers letters)
'upright staff' is the wordplay.
'upright' becomes 'post' (upright can mean a vertical post).
'staff' becomes 'man' (as in staffing or manning a particular place).
'post'+'man'='POSTMAN'
(Other definitions for postman that I've seen before include "TV's Pat, for instance" , "Male mail carrier" , "Chap with letters" , "Mail deliverer" , "No stamp needed, stangely, for this job" .)