an old hand at
a seasoned veteran
an expert in
1. She is an old hand at negotiating complex business deals.
她是处理复杂商业交易的老手。
2. As an old hand in the kitchen, he can cook anything perfectly.
作为厨房里的老手，他能把任何菜做得非常完美。
3. Don't worry, he's an old hand at dealing with such situations.
别担心，他处理这类情况非常有经验。
A: Is he new to the sales department?
A：他是销售部的新人吗？
B: No, he is an old hand; he has been here for ten years.
B：不，他是个老手；他在这里干了十年了。
1) 经验丰富的人
2) 熟练工
3) 资深人士
1. 经验丰富的人
e.g.
He's an old hand at repairing antique clocks.
他是修理古董钟的老手。
noun
1. A person who has a lot of experience in a particular activity or area.
Synonym: veteran, expert, professional