Fool about holding one sheet of paper (5)
I believe the answer is:
folio
'sheet of paper' is the definition.
(folio is a kind of sheet of paper)
'fool about holding one' is the wordplay.
'about' is an anagram indicator.
'holding' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'fool' is an anagram of 'folo'.
'folo' placed around 'i' is 'FOLIO'.
(Other definitions for folio that I've seen before include "Leaf of paper" , "Book size" , "Folded sheet - or book made from such" , "eaf" , "Body of written work" .)