A drink that starts you ruminating? (3)

I believe the answer is:

rum

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

'a drink' is the definition.
(rum is a kind of drink)

I cannot understand how the remainder of the clue works.

(Other definitions for rum that I've seen before include "Peculiar like sailor's drink (3)" , "An odd kind of drink made from molasses" , "Queer" , "Funny" , "Unusual" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app