Red oyster at sea -- it's what sailors don't want to meet? (9)
I believe the answer is:
destroyer
'what sailors don't want to meet?' is the definition.
I can't judge whether this definition defines the answer.
'red oyster at sea' is the wordplay.
'at sea' indicates an anagram.
'red'+'oyster'='redoyster'
'redoyster' with letters rearranged gives 'DESTROYER'.
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for destroyer that I've seen before include "Butcher'" , "likely to break down" , "heavily armed warship" , "killer" , "Military vessel" .)