Dreaming about many sheets (4)
I believe the answer is:
ream
'many sheets' is the definition.
'ream' can be an answer for 'sheets' (I've seen this in other clues). I am not sure about the 'many' bit.
'dreaming about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'REAM' is hidden within 'dreaming'.
Can you help me to learn more?
(Other definitions for ream that I've seen before include "Widen out (bore)" , "Many sheets - enlarge hole" , "Twenty quires of paper" , "Widen (hole); quantity of paper" , "papers" .)