Crossword Genius

One worked for a long time (3)

Ross

I believe the answer is:

eon

'long time' is the definition.
(I know that eon is a type of long time)

'one worked' is the wordplay.
'worked' indicates anagramming the letters.
'one' with letters rearranged gives 'EON'.

'for a' acts as a link.

(Other definitions for eon that I've seen before include "Major division of geological time" , "billion years" , "Immense period" , "thousand million years" , "plenty of time" .)

I've seen this clue in The Mirror.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.