Very briefly, help with the compilation of the lexicon (3,2,1,4)
I believe the answer is:
put in a word
'help with the compilation of the lexicon' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'very briefly' is the wordplay.
I cannot really understand how this works, but
'briefly' could be 'inaword' (I've seen this in another clue) and 'inaword' is present in the answer.
The remaining letters 'put' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for put in a word that I've seen before include "Recommend" , "what crossword solvers do?" .)