For Caesar, that is, time to depart (4)
I believe the answer is:
ides
'for caesar' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'that is time to depart' is the wordplay.
'that is' becomes 'id est' ('that is' in Latin).
'time' becomes 't' (abbreviation).
'to depart' suggests deleting specific letters.
'idest' with 't' taken away is 'IDES'.
Can you help me to learn more?
(Other definitions for ides that I've seen before include "Julius Caesar was killed during the . . . . of March" , "ill-fated time" , "May 15, for example" , "Julius Caesar's unlucky day in March" , "Eg March 15" .)