Chap not touching alcohol getting in rounds (4)

I believe the answer is:

otto

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'chap' is the definition.

'not touching alcohol getting in rounds' is the wordplay.
'OTTO' is hidden within the letters.
However, I'm not sure how this is indicated.

Can you help me to learn more?

(Other definitions for otto that I've seen before include "A man" , "Reversible German" , "Ger. name (palindrome)" , "perfume maker" , "He's a German, whichever way you look at it" .)

I've seen this clue in The Times.

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