、。
When it comes to sewing, she's utterly clumsy.
Literal
Sewing [quotative-という] [becoming-to-ことになると], she [topic-は] entirely clumsy-[assertion-だ]
~ということになると is a compound topic-marker meaning 'when it comes to X, as for X'. The と inside is quotative (marking the noun as a named topic), the こと nominalizes, and the になると frames the arrival at that topic as a conditional ('when we come to X'). 不器用 (ぶきよう) = clumsy, unskilled with one's hands.