Devices for shutting up after caging very loud woodpeckers (7)
I believe the answer is:
yaffles
'woodpeckers' is the definition.
(I have seen 'Green woodpeckers ' mean 'yaffles' so perhaps 'woodpeckers' could also mean 'yaffles')
'devices for shutting up after caging very loud' is the wordplay.
'devices for shutting up' becomes 'yales' (Yale is a brand of lock).
'after caging' means one lot of letters goes inside another.
'very loud' becomes 'ff' (musical abbreviation).
'yales' placed around 'ff' is 'YAFFLES'.
(Other definitions for yaffles that I've seen before include "green fliers" , "Green woodpeckers" .)