Didn’t leave as yet, prepared to assume (6,2)
I believe the answer is:
stayed on
'didn't leave' is the definition.
(I've seen this in another clue)
'as yet prepared to assume' is the wordplay.
'prepared' indicates anagramming the letters.
'to assume' becomes 'don' (I've seen this before).
'as'+'yet'='asyet'
'asyet' with letters rearranged gives 'staye'.
'staye'+'don'='STAYED ON'
(Other definitions for stayed on that I've seen before include "remained behind" , "Remained after others left" .)