You entered silly pact to be naughty (3,2)
I believe the answer is:
act up
'be naughty' is the definition.
I can't judge whether this defines the answer.
'you entered silly pact' is the wordplay.
'you' becomes 'u' (homophones).
'entered' is an insertion indicator.
'silly' is an anagram indicator.
'pact' is an anagram of 'actp'.
'u' placed inside 'actp' is 'ACT UP'.
'to' is the link.
Can you help me to learn more?
(Other definitions for act up that I've seen before include "Mess about" , "malfunction" , "Become unpleasant" , "Behave badly, cause trouble - like thespian?" , "Behave badly, give trouble" .)