Spool back on air (6)
I believe the answer is:
rewind
'spool back' is the definition.
The definition suggests a singular noun which matches the answer.
'on air' is the wordplay.
'on' becomes 're' (regarding).
'air' becomes 'wind'.
're'+'wind'='REWIND'
Can you help me to learn more?
(Other definitions for rewind that I've seen before include "Return to start of film" , "Turn (a tape) backwards" , "Coil back to the beginning" , "Turn back a film or tape" , "Operate tape" .)