Answer: impairs

AnswerCrossword Clue
IMPAIRSMakes less effective
IMPAIRSSpoils
IMPAIRSWeakens
IMPAIRSDamages.
IMPAIRSDamages
IMPAIRSVitiates
IMPAIRSDebilitates
IMPAIRSHampers
impairsIMPAIR, to damage or weaken, also PAIRE
impairsWeaken or damage something (esp. a human faculty or function)