Tiny bit of lettuce stuck in dentures unfortunately — that's what happened (3,6)
I believe the answer is:
Here is my best explanation:
'that's what happened' is the definition.
'tiny bit of lettuce stuck in dentures unfortunately' is the subsidiary indication.
'tiny bit of' indicates taking the first letters.
'stuck in' is an insertion indicator.
'unfortunately' indicates an anagram.
The first letter of 'lettuce' is 'l'.
'dentures' with letters rearranged gives 'endresut'.
'l' going within 'endresut' is 'endresult'.
(Other definitions for end result that I've seen before include "Latest", "Final outcome", "Outcome", "Eldest run to reach final outcome", "Final product" and "Elders run to find ultimate consequence".)