Construct perpendicular (5)
I believe the answer is:
erect
I believe this clue is a double definition.
'construct' is the first definition.
(I know that erect is a more specific form of construct)
'perpendicular' is the second definition.
(synonyms)
(Other definitions for erect that I've seen before include "Build, set up" , "Upstanding" , "Build, put up" , "Found" , "Crete (anag)" .)