Godan verb with 'mu' ending, Intransitive verb
to grapple with; to wrestle with; to engage in a bout; to be matched against
そろそろ本気で仕事に取り組むころだよ。It is time you get down to work. to tackle (e.g. a problem); to come to grips with; to work hard on
Also written 取組む【とりくむ】