Let's play havoc, starting to monkey around! (3,2)
I believe the answer is:
hit it
'let's play' is the definition.
I know nothing about this answer so I can't judge whether this works.
'havoc starting to monkey around' is the wordplay.
'starting' indicates taking the first letters.
'to monkey' becomes 'titi' (titi is a kind of monkey).
'around' shows that the letters should be reversed in order.
The initial letter of 'havoc' is 'h'.
'titi' backwards is 'itit'.
'h'+'itit'='HIT IT'
Can you help me to learn more?
(Other definitions for hit it that I've seen before include "'But WG - - for six!'" , "Come to the right conclusion" .)