The firm left to slip into bankruptcy (8)
I believe the answer is:
collapse
'bankruptcy' is the definition.
(thesaurus)
'the firm left to slip' is the wordplay.
'the firm' becomes 'co' (a firm is a company).
'left' becomes 'l' (common abbreviation).
'to slip' becomes 'lapse' (lapsing is a kind of slipping**).
'co'+'l'+'lapse'='COLLAPSE'
'into' acts as a link.
(Other definitions for collapse that I've seen before include "Suddenly fall down or give way" , "Give way or cave in" , "downfall" , "Go to ruin" , "Fall down as from weakness" .)