Straight post (7)
I believe the answer is:
upright
This clue is a double definition.
'straight' is the first definition.
('upright' can be a synonym of 'straight')
'post' is the second definition.
(thesaurus)
(Other definitions for upright that I've seen before include "Keyboard instrument" , "In a vertical position" , "Standing straight up" , "Key item" , "Pig hurt (anag) -- noble" .)