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Is there anything to drink in the refrigerator?
Literal
Refrigerator [in-に] something drink [subject-が] exists [question-か].
何か飲み物 ('something drinkable') combines 何か ('something') with the noun 飲み物 ('drink, beverage'). 飲み物 is a verb-stem+物 compound, productive across the language: 読み物 ('reading material'), 書き物 ('writing'), 食べ物 ('food'). 何か can stand alone or modify a following noun — here it modifies 飲み物.