The term 'chink in the armor, say' can be solved by the crossword clue 'FLAW' (4 letters). This phrase is used to describe a weakness or vulnerability in something that was previously thought to be strong or impenetrable. It is often used in the context of a person's character or a plan that has been carefully thought out. The phrase is derived from the idea of a chink in a suit of armor, which would make it vulnerable to attack.