Before the first, everyone is in bad with the poet (9)

'the poet' is the definition.
(thesaurus)

'before the first everyone is in bad' is the wordplay.
'before' is a charade indicator (letters next to each other).
'the first' becomes 'ist' (ist resembles 1st).
'everyone' becomes 'all' (all people).
'is in' indicates putting letters inside.
'all' inserted into 'bad' is 'ballad'.
'ist' after 'ballad' is 'BALLADIST'.

'with' acts as a link.