(often + with) to engage in hand-to-hand fighting; to wrestle
(+ with) to struggle to deal successfully with something
She has spent the last three hours grappling with a mathematical problem
to seize and wrestle with (somebody)
to seize (something) with, or as if with, a grapnel
archaic or literary to seize or lay hold of (something) and attach it firmly with or as if with a grapnel
Those friends thou hast … grapple them unto thy soul with hoops of steel — Shakespeare
grappler noun