... he died here, content to leave oils, see (4)
I believe the answer is:
oslo
'he died here' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'content to leave oils see' is the wordplay.
'content to leave' suggests removing the centre (the contents of the word are removed).
'see' becomes 'lo' (archaic word meaning 'look!').
'oils' with its centre taken out is 'os'.
'os'+'lo'='OSLO'
Can you help me to learn more?
(Other definitions for oslo that I've seen before include "where Ibsen lived under another name" , "Go solo to European capital" , "Solo in Norway?" , "Norwegian chief port" , "foreign port" .)