Ambition to have job that's upright (8)
I believe the answer is:
goalpost
'that's upright' is the definition.
(goalpost is a kind of upright)
'ambition to have job' is the wordplay.
'ambition' becomes 'goal' (I've seen this in another clue).
'to have' says to put letters next to each other.
'job' becomes 'post' (post is a kind of job).
'goal'+'post'='GOALPOST'
(Other definitions for goalpost that I've seen before include "woodwork" , "Upright with net attached" , "One of four supporters at ends of pitch" , "One propping up the bar" , "it's unfair to move" .)