Learn Croatian: On želi usavršiti kroj odijela. - He wants to perfect the cut of the suit.

It is built from the adjective savršen (perfect). Following the pattern from this lesson, the prefix u- and the suffix -iti are added to the adjective's root (savrš-, dropping the -en ending) to create usavršiti, which means 'to make perfect' or 'to perfect'.

Is usavršiti perfective or imperfective?

It is perfective, focusing on the completed result of making something perfect. If you wanted to talk about an ongoing process (e.g., 'He is perfecting the cut'), you would use its imperfective equivalent, usavršavati.

Why does odijela end in '-a' here? Is it plural?

No, it is singular. It acts as a possessive, modifying kroj (cut) to mean 'the cut of the suit'. Because it describes what the cut belongs to, the neuter noun odijelo takes the genitive singular ending -a.

What case is kroj in, and why does it look exactly like the dictionary form?

The word kroj (cut) is the direct object of the verb usavršiti, so it is in the accusative case. Because it is an inanimate masculine noun, its accusative form is identical to its nominative form.