。
She wore a kimono that men would gaze at admiringly.
Literal
She [topic-は] men [subject-が] enchanted-do [like-ような] kimono [object-を] was-wearing.
ほれぼれとする is a 擬態語 (state mimetic) verb derived from the mimetic root ほれぼれ ('fondly, admiringly, with adoration'), built into a verb with と+する — the と here is adverbial, the standard way mimetics attach to verbs. The whole clause 男性がほれぼれとするような ('such that men become enchanted') is a relative clause modifying 着物 ('kimono'); ような is the attributive form of ようだ used for similes and qualitative descriptions. 着物 carries cultural weight — it's the traditional Japanese garment, so the image evoked is one of striking, classical elegance.