Worker ate about noon (4)
I believe the answer is:
hand
'worker' is the definition.
(hand is a kind of worker)
'ate about noon' is the wordplay.
'ate' becomes 'had' (e.g. I had an ice cream).
'about' means one lot of letters goes inside another.
'noon' becomes 'n' (abbreviation for noon).
'had' placed around 'n' is 'HAND'.
(Other definitions for hand that I've seen before include "Worker; pointer" , "Worker - four inches - bunch of bananas" , "employee" , "Help < and applause" , "Round of applause" .)