Ensure boat is at sea in coastal resort (10)
I believe the answer is:
eastbourne
'coastal resort' is the definition.
'eastbourne' can be an answer for 'resort' (I've seen this before). I'm not certain of the 'coastal' bit.
'ensure boat is at sea' is the wordplay.
'is at sea' indicates anagramming the letters.
'ensure'+'boat'='ensureboat'
'ensureboat' with letters rearranged gives 'EASTBOURNE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for eastbourne that I've seen before include "Resort in East Sussex" , "somewhere on the south coast" , "popular retirement venue" , "Sussex coastal town" , "Resort close to Beachy Head" .)