Fly in the __ Means a Drawback or a Flaw

Puzzle 11 of Fandom Easy Pack

Question is: Fly in the __ Means a Drawback or a Flaw

and the answer is: OINTMENT

Word Meaning:

OINTMENT — (medicine) A viscous preparation of oils and/or fats, usually containing medication, used as a treatment or as an emollient.

Definitions from Wiktionary.