Jack and I cutting large avocado initially for Mexican dish (6)
I believe the answer is:
fajita
'mexican dish' is the definition.
(I've seen this before)
'jack and i cutting large avocado initially' is the wordplay.
'jack' becomes 'J' (playing card abbreviation).
'and' says to put letters next to each other.
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'large' becomes 'fat' (I've seen this in other clues).
'initially' suggests taking the first letters.
The initial letter of 'avocado' is 'a'.
'j'+'i'='ji'
'ji' placed inside 'fat' is 'fajit'.
'fajit'+'a'='FAJITA'
'for' acts as a link.
(Other definitions for fajita that I've seen before include "Mexican meat strip" , "Cooked meat or vegetables served with a soft tortilla and grated cheese" , "Soft tortilla with filling and grated cheese" , "Wrapped Mexican dish" .)