、。
She worked very hard to finish the job by the deadline.
Literal
She [topic-は] deadline [by-までに] work [object-を] finish [purpose-ようと], greatly worked-hard.
The volitional + と (仕上げようと) marks purpose: 'in order to finish.' ~までに ('by/before the deadline') sets the time constraint. 大いに ('greatly / very much') is a literary intensifier — more emphatic than とても. がんばる ('to do one's best / work hard') in hiragana rather than the kanji 頑張る is common in informal writing.