Efficient ways to live in advanced years, after retirement (8)

'efficient ways' is the definition.
The answer and definition can be both locations as well as being plural nouns.
Perhaps they are linked in a way I don't understand?

'live in advanced years after retirement' is the wordplay.
'live' becomes 'be' (synonyms).
'in advanced years' becomes 'senile' (I can't justify this - if you can you should believe this answer much more).
'after retirement' says the letters should be written backwards.
'senile' written backwards gives 'elines'.
'be'+'elines'='BEELINES'

'to' is the link.

Can you help me to learn more?