An upright position (4)
I believe the answer is:
post
This clue is a double definition.
'an upright' is the first definition.
(upright can mean a vertical post)
'position' is the second definition.
(I know that position can be written as post)
(Other definitions for post that I've seen before include "Job; upright timber" , "Letters and parcels; job" , "Publish' mail' job" , "Member < to comment on website" , "Prefix meaning after" .)