Fateful day in Senate that is ending early (4)
I believe the answer is:
ides
'fateful day in senate that is ending early' is the definition.
'ides' can be an answer for 'fateful day' (ides of March, date of Caesar's assassination). I am not certain of the remainder of the definition.
'that is ending early' is the wordplay.
'that is' becomes 'id est' ('that is' in Latin).
'ending early' means to remove the last letter.
'idest' with its final letter taken off is 'IDES'.
Can you help me to learn more?
(Other definitions for ides that I've seen before include "May 15, for example" , "Unlucky day for Julius Caesar" , "Julius Caesar died in these March days" , "March day fatal to Julius Caesar" , "Caesar's fateful days" .)