A flight, of course, usually ends with a landing (6)
I believe the answer is:
stairs
'a landing' is the definition.
(thesaurus)
'a flight of course' is the wordplay.
'a flight' becomes 'stair' (I've seen this before).
'of course' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'stair'+'s'='STAIRS'
'usually ends with' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for stairs that I've seen before include "Access consisting of steps" , "Series of steps" , "Ascending flight of steps" , "Means of ascent/descent" , "A flight of indoor steps" .)