Having left before you depart (7)
I believe the answer is:
testate
'having left' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives can occasionally define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for testate that I've seen before include "With a legally valid will" , "Person willing" , "Having made a will before death" , "State of having made a will" , "Having made a valid will" .)