Answer: arduous

AnswerCrossword Clue
ARDUOUSDifficult
ARDUOUSHerculean
ARDUOUSTrying
ARDUOUSBurdensome
ARDUOUSBackbreaking
ARDUOUSTough to accomplish
ARDUOUSLaborious.
ARDUOUSDifficult to do.
ARDUOUSStrenuous.
ARDUOUSToilsome.
ARDUOUSHard.
ARDUOUSGruelling
ARDUOUSDemanding
arduousvery difficult
arduoushard to accomplish or achieve difficult years of arduous training