Crossword Genius

Ordering a drink and noticing its ingredients (3,3,5)

Ross

I believe the answer is:

gin and tonic

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

'ordering' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'a drink and noticing its ingredients' is the wordplay.
'and noticing' can be anagrammed to 'GIN AND TONIC'.
However, I am unsure how the anagram is indicated.

Can you help me to learn more?

(Another definition for gin and tonic that I've seen is " Common cocktail".)

I've seen this clue in The Globe and Mail.
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