Nothin (4)
'nothin'' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nada that I've seen before include "zip" , "Not a sausage" , "Nothing (US)" , "Love" .)
(Other definitions for zilch that I've seen before include "Diddly-squat" , "Sweet FA (slang)" , "Nothing (American)" , "Nil" , "15" .)