。
She tugged on my shirt.
Literal
She [topic-は] my shirt [object-を] pulled.
引っ張る ('pull, tug') applies as readily to clothing as to body parts. シャツ ('shirt') is the loanword form, fully standard in Japanese — the native 着物 (kimono) refers to traditional Japanese garments, while everyday Western-style shirts use シャツ. The を here marks the shirt as the direct object of the tug, the same structure Japanese uses for body-part tugging (手を引く, 袖を引く).