Crossword Genius

A big error when the communication’s not timed (4)

Ross

I believe the answer is:

mess

I'm a little stuck... Click here to teach me more about this clue!

'a big error' is the definition.
'mess' can be an answer for 'error' (thesaurus). I am not certain of the 'a big' bit.

'when the communication's not timed' is the wordplay.
I cannot quite understand how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
'communication's' could be 'ms' (ms is a kind of communication) and 'ms' is found within the remaining letters.
A single letter 's' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for mess that I've seen before include "Canteen - muddle" , "dirty and unpleasant" , "Untidy muddle" , "terrible state" , "State of confusion or untidiness" .)

I've seen this clue in the Evening Standard.
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