Questionable saying about nothing (4)
I believe the answer is:
moot
'questionable' is the definition.
(I've seen this in another clue)
'saying about nothing' is the wordplay.
'saying' becomes 'mot' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
'mot' placed around 'o' is 'MOOT'.
Can you help me to learn more?
(Other definitions for moot that I've seen before include "Propose for discussion" , "Such a point is arguable" , "Such a point is disputable" , "Anglo-Saxon assembly; subject to debate" , "Undecided as a debatable point may be" .)