あまり得意じゃ

not very good at

→ 余り
phrase Rare #23,949
not very good at Usually followed by ない or ないです. あまり〜ない means “not very,” and 得意 means being good at or skilled in something.
JA: 私は料理があまり得意じゃない。
EN: I'm not very good at cooking.

紅茶あまり得意じゃないんです

I'm not really a fan of black tea.

お肉あまり得意じゃない野菜の準備はあるのか

Are there any vegetable options for someone who isn’t very good with meat?

— 紅夢 (1991)

トム泳ぐのあまり得意じゃないよ

Tom isn't very good at swimming.

フランス語あまり得意じゃないんでしょう

You're not very good at French, are you?

料理はあまり得意じゃないんでしょう

You're not very good at cooking, are you?

残念だけどダンスあまり得意じゃないんだ

Unfortunately, I'm not very good at dancing.

これはあまり得意じゃないんだ

I'm not very good at this.