Affixed in an unnatural way (5)
This clue is a double definition.
'affixed' is the first definition.
(I've seen this before)
'in an unnatural way' is the second definition.
(I've seen this before)
(Other definitions for put on that I've seen before include "Apply (to a surface) - present (on stage)" , "Increase as with weight" , "in an unnatural way" , "Donned" , "Don; mount (a play)" .)
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?