勉強に

for study

→ 勉強
phrase Common #7,390
for study 勉強に来る means “to come to study.” In 勉強になる, the に is part of the expression meaning “to be instructive” or “to learn something from it.”
JA: 図書館へ勉強に行きます。
EN: I’m going to the library to study.

トム勉強にまじめでない

Tom isn't serious about his studies.

時間は仕事余暇勉強に配分されている

Time is divided among work, leisure, and study.

勉強に最もよい季節のは言うまでもない

It goes without saying that autumn is the best season for studying.

だけどそれと君の勉強に何の関係が

But what does that have to do with your studies?

— パラサイト 半地下の家族 (2019)

勉強に努力は欠かせない

Effort is essential for studying.

ここに勉強に来ます

I come here to study.

私は勉強に疲れた

I'm tired from studying.

ジョージ勉強に真剣でない

George isn't serious about his studies.

私たちは学校の勉強に多くの時間を当てた

We devoted a lot of time to our schoolwork.

私は勉強に飽きている

I’m tired of studying.

屋外の音気になって勉強に集中できない

I can't concentrate on studying because the noise outside is distracting me.