Equus perhaps includes some silly acting (9)
I believe the answer is:
horseplay
'equus perhaps' is the definition.
(Equus is a play partly about horses)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for horseplay that I've seen before include "rough and tumble" , "clowning around" , "Buffoonery" , "Boisterous rowdy recreation" , "Rough boisterous behaviour" .)