Quietly talk about the open spaces
I believe the answer is:
gaps
'the open spaces' is the definition.
(I've seen this in another clue)
'quietly talk about' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'talk' becomes 'gas' (gas can mean to chat).
'about' means one lot of letters goes inside another.
'p' put into 'gas' is 'GAPS'.
(Other definitions for gaps that I've seen before include "Breaks, spaces" , "Breaks or openings as in hedge or fence" .)