Two thirds of timetable cut — when is the train due? (3)
I believe the answer is:
eta
'the train due?' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'two thirds of timetable cut when' is the wordplay.
'ETA' is hidden in amongst the letters.
But, I'm unsure how the hidden word is indicated.
'is' is the link.
Can you help me to learn more?
(Other definitions for eta that I've seen before include "Member of Greek set a" , "Militants" , "Greek H" , "Basque separatist movement" , "when you can hope to receive it" .)