One worked for some time (3)
I believe the answer is:
eon
'some time' is the definition.
(eon is a kind of time)
'one worked' is the wordplay.
'worked' indicates anagramming the letters.
'one' with letters rearranged gives 'EON'.
'for' acts as a link.
(Other definitions for eon that I've seen before include "billion years" , "In time, long division" , "Prolonged period" , "Vast period" , "Immense period" .)