Convene again (5)
I believe the answer is:
resit
'convene again' is the definition.
('sit' is an answer for 'convene' so perhaps 'resit' is OK for 'convene again')
This is all the clue.
(Other definitions for resit that I've seen before include "second exam" , "Student's test" , "Enquiring intrusively (into person's affairs)" , "tested again" , "repeated test" .)