Ancient writer of wild sea music (5)
I believe the answer is:
aesop
'ancient writer' is the definition.
'aesop' can be an answer for 'writer' (I've seen this before). I am not certain of the 'ancient' bit.
'wild sea music' is the wordplay.
'wild' is an anagram indicator.
'music' becomes 'op' (I can't explain this - if you can you should give a lot more credence to this answer).
'sea' anagrammed gives 'aes'.
'aes'+'op'='AESOP'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for aesop that I've seen before include "Greek father of fables" , "So ape the writer of fables" , "Greek author of fables (c 620-560 BC)" , "Great Greek teller of animal fables" , "Classic fable writer" .)