Worker in charge of playful behaviour (5)
I believe the answer is:
antic
'playful behaviour' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'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.
Can you help me to learn more?
(Other definitions for antic that I've seen before include "Caper, trick" , "Mad act done for fun" , "Caper; grotesque (arch.)" , "Tomfoolery" , "Prank" .)