Liable to slip up with account I had open, rent going astray (8,5)
I believe the answer is:
accident-prone
'liable to slip up' is the definition.
'account i had open rent going astray' is the wordplay.
'account' becomes 'acc'.
'i had' becomes 'id' (I'd).
'going astray' indicates an anagram.
'open'+'rent'='openrent'
'openrent' with letters rearranged gives 'entprone'.
'acc'+'id'+'entprone'='ACCIDENT-PRONE'
'with' acts as a link.
(Other definitions for accident-prone that I've seen before include "With a Tendency to suffer misfortune" , "Given to misadventure" , "Unusually susceptible to mishaps" , "Liable to have mishaps" , "Susceptible to mishap" .)