That old space station will show its years, if only in illusion (6)
I believe the answer is:
mirage
'illusion' is the definition.
(I've seen this before)
'that old space station will show its years if only' is the wordplay.
I cannot quite see how this works, but
'years' could be 'age' (period of many years) and 'age' is located in the answer.
'space station' could be 'mir' (I've seen this in another clue) and 'mir' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for mirage that I've seen before include "illusory thing" , "Illusory image" , "vision" , "Something illusory and unattainable" , "It doesn't exist" .)