Reveals quiet study, fully extended (9)
I believe the answer is:
outspread
'fully extended' is the definition.
(I've seen this before)
'reveals quiet study' is the wordplay.
'reveals' becomes 'outs' (outing is a kind of revealing).
'quiet' becomes 'p' (music symbol for 'piano').
'study' becomes 'read' ('read' can be a synonym of 'study').
'outs'+'p'+'read'='OUTSPREAD'
(Other definitions for outspread that I've seen before include "Fully extended" , "Scattered" , "Wide apart" .)