Missing worker rings bosses from time to time (6)
I believe the answer is:
'missing' is the definition.
(similar in meaning)
'worker rings bosses from time to time' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'rings' means one lot of letters goes inside another.
'from time to time' indicates alternate letters (letters removed on a regular basis).
The alternating letters of 'bosses' are 'bse'.
'ant' going around 'bse' is 'ABSENT'.
(Other definitions for absent that I've seen before include "Not present or focused", "nowhere to be seen", "lack of attention", "AWOL", "Not where one should be".)