Bill in old accommodation set up again from the start (2,4)
I believe the answer is:
da capo
'again from the start' is the definition.
(musical term)
'bill in old accommodation set up' is the wordplay.
'bill' becomes 'ac' (short for account).
'in' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'accommodation' becomes 'pad' (I've seen this in other clues).
'set up' says the letters should be written backwards (in a down clue, letters go up).
'o'+'pad'='opad'
'ac' placed inside 'opad' is 'opacad'.
'opacad' in reverse letter order is 'DA CAPO'.
(Other definitions for da capo that I've seen before include "(In music) repeat from the beginning" , "Back to the start" .)