Notes glue is affected in flood (6)
I believe the answer is:
deluge
'flood' is the definition.
('deluge' can be a synonym of 'flood')
'notes glue is affected in' is the wordplay.
'notes' becomes 'de' (**).
'is affected' indicates an anagram.
'in' means one lot of letters goes inside another.
'glue' anagrammed gives 'elug'.
'de' placed around 'elug' is 'DELUGE'.
(Other definitions for deluge that I've seen before include "Cloudburst, downpour" , "Flooding downpour" , "Torrential rain" , "Great flood" , "Inundation" .)