English team in large firm chart last of May and Johnson's work (12)
I believe the answer is:
lexicography
'english team in large' is the definition.
I can't judge whether this defines the answer.
'firm chart last of may and johnson's work' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'chart' becomes 'graph' (I've seen this before).
'last of' says to take the final letters.
'and' says to put letters next to each other (I've seen this in other clues).
'johnson's work' becomes 'lexi' (I can't justify this - if you can you should give a lot more credence to this answer).
The last letter of 'may' is 'y'.
'co'+'graph'+'y'='cography'
'cography' after 'lexi' is 'LEXICOGRAPHY'.
Can you help me to learn more?
(Other definitions for lexicography that I've seen before include "Process of dictionary compilation" , "Dictionary making" , "Dictionary compiling" , "The compilation of dictionaries" , "The compiling of dictionaries" .)