My parse's wrong, assuming 2's first letter is M? (9)
I believe the answer is:
spymaster
'my parse's wrong assuming' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'2's first letter is m?' is the wordplay.
I cannot really see how this works, but
'2's' could be 's' and 's' is found within the answer.
'first' could be 'a' (first letter of the alphabet) and 'a' is present in the answer.
'letter' could be 'y' (Y is a letter of the alphabet) and 'y' is located in the answer.
'm?' could be 'm' and 'm' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for spymaster that I've seen before include "head of 6?" , "Messy part (anag) - M?" , "007's boss?" , "Eg, head of MI6" , "Eg, Bond's M" .)