Most suitable business agreement supporting auditor's view (5)
I believe the answer is:
ideal
'most suitable' is the definition.
(I've seen this before)
'business agreement supporting auditor's view' is the wordplay.
'business agreement' becomes 'deal' (I've seen this in another clue).
'supporting' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'auditor's' shows a homophone (sound like).
'view' becomes 'eye' (I've seen this before).
'eye' sounds like 'i'.
'deal' after 'i' is 'IDEAL'.
(Other definitions for ideal that I've seen before include "supreme" , "Exemplar" , "Ailed (anag)" , "Model of ethical behaviour" , "Model of excellance" .)