Crossword Genius

Bitter additive for seasick argonauts (9)

Ross

I believe the answer is:

angostura

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'bitter additive' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.

'seasick argonauts' is the wordplay.
'argonauts' anagrams to 'ANGOSTURA'.
Though, I am unsure how this is indicated.

'for' is the link.

Can you help me to learn more?

(Other definitions for angostura that I've seen before include "It makes 8 pink" , "bitter substance" , "An aromatic bark, made bitter tonic" , "Bitters for 13" , "Bitter stuff for Argonauts" .)

I've seen this clue in the Sydney Morning Herald.
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