Part of staircase in corridor is erected (5)
I believe the answer is:
riser
'part of staircase' is the definition.
('riser' is part of 'staircase')
'in corridor is erected' is the wordplay.
'in' indicates the answer is hidden within the clue.
'RISER' is hidden in the letters of 'corridor is erected'.
(Other definitions for riser that I've seen before include "person advancing position?" , "He gets up" , "Pipe for upward flow" , "Face of a step" , "Stair front" .)