。
She is tackling that issue.
Literal
She [topic-は] that issue [at-に] is-grappling.
取り組む is a compound verb literally 'to grasp and grapple' — its imagery comes from sumo, where 取り組み means a wrestling match. It takes its target with に, parallel to 直面する ('face') and 立ち向かう ('confront'). The ~ている form here marks ongoing engagement: she's currently in the process of working on the issue, not just occasionally giving it thought. Common in news and policy writing for describing serious efforts on a problem.