Crossword Genius

Best device, kept below the counter, is not designed to be portable (7,8)

Ross

I believe the answer is:

desktop computer

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

'best device' is the definition.
'desktop computer' can be an answer for 'device' (desktop computer is a kind of device). I'm not sure about the 'best' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Another definition for desktop computer that I've seen is " electronic organiser".)

I've seen this clue in The Irish Times.
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