a chink in somebody's armour
chink in (one's)/the armor
A minor but very detrimental flaw or weakness. Yeah, he's brilliant, but his violent temper has destroyed many business relationships—it's a real chink in his armor. The criminal's tendency to use his own cell phone to conduct business was the chink in the armor the police needed to put him in jail.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a chink in somebody’s ˈarmour(British English) (American English a chink in somebody’s ˈarmor) a weakness in somebody’s argument, character, etc., that can be used in an attack: The one chink in her armour is the lack of a sense of humour. She hates people laughing at her.
A chink is a small hole.
Farlex Partner Idioms Dictionary © Farlex 2017