Crossword Genius

It keeps one going when all at sea (6,4)

Ross

I believe the answer is:

engine room

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

'all at sea' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'it keeps one going when' is the wordplay.
I cannot really understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

(Other definitions for engine room that I've seen before include "Source of strength" , "Source of naval power" , "basis of the Navy's power?" , "hub of activity" .)

I've seen this clue in The Guardian.
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