Answer: thwarts

AnswerCrossword Clue
THWARTSStymies
THWARTSObstructs
THWARTSRuins the plans of
THWARTSShort-circuits
THWARTSFrustrates.
THWARTSFoils
THWARTSFrustrates
thwartsTHWART, to prevent or hinder
thwartsto oppose or frustrate