Definitely that crooked Simon is on the take (2,7)
I believe the answer is:
no mistake
'definitely' is the definition.
I know nothing about this answer so I can't judge whether this works.
'crooked simon is on the take' is the wordplay.
'crooked' indicates an anagram.
'is on' says to put letters next to each other.
'simon' with letters rearranged gives 'nomis'.
'nomis'+'take'='NO MISTAKE'
'that' acts as a link.
Can you help me to learn more?
(Another definition for no mistake that I've seen is " Take Simon (anag) - that is definite".)