Tough wings less than sound (7)
I believe the answer is:
thunder
'sound' is the definition.
(I know that thunder is a type of noise)
'tough wings less than' is the wordplay.
'wings' says to hollow out the word (remove centre letters) (the wings or edge letters of the word are used).
'less than' becomes 'under' (eg under a certain number).
'tough' with its middle removed is 'th'.
'th'+'under'='THUNDER'
(Other definitions for thunder that I've seen before include "Deep rumbling sound" , "Loud rumbling sound" , "Meteorological rumblings" , "Boom; bellow" , "Move fast, noisily, and heavily" .)