Sea song won't be performed in ramshackle area (10)
I believe the answer is:
shantytown
'ramshackle area' is the definition.
(I've seen this before)
'sea song won't be performed in' is the wordplay.
'sea song' becomes 'shanty' (I've seen this before**).
'be performed' indicates an anagram (I've seen 'is performed' mean this).
'in' is an insertion indicator.
'wont' with letters rearranged gives 'town'.
'shanty' placed within 'town' is 'SHANTYTOWN'.
(Other definitions for shantytown that I've seen before include "Deprived area of very poor housing" , "Area with ramshackle buildings" , "area of ramshackle housing" , "Deprived urban area of run-down huts" , "Collection of poor dwellings" .)