Digit I got wrong in binomial equation at first (3,3)
I believe the answer is:
big toe
'digit' is the definition.
(I know that big toe is a type of toe)
'i got wrong in binomial equation at first' is the wordplay.
'wrong' indicates anagramming the letters.
'in' indicates putting letters inside.
'at first' indicates taking the first letters.
The first letters of 'binomial equation' is 'be'.
'i'+'got'='igot'
'igot' anagrammed gives 'igto'.
'igto' placed within 'be' is 'BIG TOE'.
(Other definitions for big toe that I've seen before include "Corn grows here" , "Largest pedal extremity" , "that once went to market?" , "member of the body" , "Largest foot digit" .)