On start and close of conference, took on Rome, returning yet again (4,4)

'again' is the definition.
(synonyms)

'on start and close of conference took on rome returning' is the wordplay.
'start' becomes 'c' (I can't explain this - if you can you should believe this answer much more).
'and' is a charade indicator (letters next to each other).
'close of' says to take the final letters (the letter which ends or closes the word).
'took on' is a charade indicator (letters next to each other).
'returning' says the letters should be written in reverse.
The final letter of 'conference' is 'e'.
'e'+'rome'='erome'
'erome' written backwards gives 'emore'.
'on'+'c'+'emore'='ONCE MORE'

'yet' acts as a link.
This may not be correct. It may belong to another bit of the clue.

Can you help me to learn more?