Playful act of worker in charge (5)
I believe the answer is:
antic
'playful act' is the definition.
(I've seen this in another clue)
'worker in charge' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'ant'+'ic'='ANTIC'
'of' is the link.
(Other definitions for antic that I've seen before include "old buffoon" , "Caper, trick" , "Playful or mischievous act" , "Caper; grotesque (arch.)" , "Tomfoolery" .)