Folded in half then turned back sides of origami paper (5)
I believe the answer is:
folio
'paper' is the definition.
(folio is a kind of paper)
'folded in half then turned back sides of origami' is the wordplay.
'folded in half then' becomes 'fol' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'turned back' is a reversal indicator.
'sides of' says to hollow out the word (remove centre letters) (only the letters on the sides remain).
'origami' with its centre removed is 'oi'.
'oi' written backwards gives 'io'.
'fol'+'io'='FOLIO'
Can you help me to learn more?
(Other definitions for folio that I've seen before include "Four pages" , "Body of written work" , "Book made of folded sheets" , "Leaf of paper" , "Two-leaf sheet" .)
