Second nuclear weapon is very loud (8)
I believe the answer is:
strident
'very loud' is the definition.
'strident' can be an answer for 'loud' (thesaurus). I am not certain of the 'very' bit.
'second nuclear weapon' is the wordplay.
'second' becomes 's' (common abbreviation).
'nuclear weapon' becomes 'trident' (I've seen this before).
's'+'trident'='STRIDENT'
'is' is the link.
Can you help me to learn more?
(Other definitions for strident that I've seen before include "Unpleasantly loud and harsh" , "Harsh, grating" , "Harsh in tone" , "harsh noise" , "making loud noises" .)