Measuring device worker tracks sometime in autumn? (6)
I believe the answer is:
octant
'measuring device' is the definition.
(I've seen this in another clue)
'worker tracks sometime in autumn?' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'tracks' says to put letters next to each other (some letters track or go after others).
'sometime in autumn?' becomes 'Oct' (October).
'ant' after 'oct' is 'OCTANT'.
(Other definitions for octant that I've seen before include "Device to measure angles to a celestial body" , "segment of disc" , "Eighth part of circle" , "45 degrees" .)