Small window in stairs blocked by cane, essentially (8)
I believe the answer is:
fanlight
'small window' is the definition.
(I've seen this before)
'stairs blocked by cane essentially' is the wordplay.
'stairs' becomes 'flight' (flight is a kind of stairs).
'blocked by' means one lot of letters goes inside another (block can mean to plug a gap in something).
'essentially' indicates the central letters.
The centre of 'cane' is 'an'.
'flight' placed around 'an' is 'FANLIGHT'.
'in' acts as a link.
(Other definitions for fanlight that I've seen before include "kind of window" , "upper window?" , "Windows above a door" , "elevated aperture" , "It enables us to see" .)