Small missile making shrill noise (8)
I believe the answer is:
strident
'shrill noise' is the definition.
'strident' can be an answer for 'noise' (I have seen 'harsh noise' mean 'strident' so perhaps 'noise' could also mean 'strident'). I am not certain of the 'shrill' bit.
'small missile' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'missile' becomes 'Trident' (UK nuclear weapons system).
's'+'trident'='STRIDENT'
'making' acts as a link.
Can you help me to learn more?
(Other definitions for strident that I've seen before include "harsh sound" , "Unpleasantly rough" , "making loud noises" , "Grating - urgent" , "Loud and harsh over tridents" .)