One out of bed seen going upstairs (5)
I believe the answer is:
riser
'one out of bed' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for riser that I've seen before include "Front of a step; vertical pipe" , "Vertical piece between two stair treads" , "Face of a step" , "upright portion of step" , "Upright piece in stairs" .)