One absorbed by Sun's flight feature (5)
I believe the answer is:
stair
'flight feature' is the definition.
(I've seen this in another clue)
'one absorbed by sun's' is the wordplay.
'one' becomes 'i' (Roman numeral).
'absorbed by' indicates putting letters inside.
'sun' becomes 'star' (I've seen this before).
'i' placed into 'star' is 'STAIR'.
(Other definitions for stair that I've seen before include "section of flight" , "Tread and riser" , "Component of flight" , "One step in a series" , "Tarsi (anag)" .)