Standing straight (5)
'standing straight' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for erect that I've seen before include "Upright; put up" , "Build - straight up" , "Build, upright" , "Construct - perpendicular" , "Unbowed" .)
(Other definitions for upright that I've seen before include "Type of piano" , "Standing straight up" , "Joanna" , "beyond reproach" , "Pole; principled" .)