Verb (5-dan, く, intransitive)
1.  to cling to;  to hold on to;  to hold fast to
2.  to grapple
3.  to set about doing;  to begin;  to commence;  to undertake
4.  to take hold of;  to possess;  to haunt
of a demon, thought, emotion, etc.
5.  to obtain a clue;  to get a lead