Dreaming about some sheets (4)
I believe the answer is:
ream
'sheets' is the definition.
(I've seen this before)
'dreaming about some' is the wordplay.
'some' indicates a hidden word.
'REAM' is hidden in the letters of 'dreaming about'.
(Other definitions for ream that I've seen before include "480 sheets of paper" , "Twenty quires of paper" , "Widen (hole) with borer; twenty quires" , "500 sheets, perhaps" , "stock of paper" .)