Crossword Genius

Perverse aversion to whisky (7,3,5)

Ross

I believe the answer is:

against the grain

'perverse' is the definition.
(both can mean unconventional)

I cannot understand how the remainder of the clue works.

(Other definitions for against the grain that I've seen before include "hostile to principles?" , "not for a malt whisky drinker" , "Joiners sometimes saw this" , "Following the difficult route" , "Out of character" .)

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