the skills and methods used by people who work for organizations involved in secret activities such as intelligence and spying (= finding out secret information about enemies and competitors) or terrorism (= violent political crime)

For years they used the same planes, with the same registration numbers, to carry out secret missions, which was not good tradecraft. 多年来，他们用同样的飞机、同样的注册号来执行秘密任务，这可不是好的谍战技术。

the skills and methods used by someone doing a particular skilled job

My mentor, Professor Jane Slater, taught me the basic "tradecraft" of history. 我的导师简·斯莱特教授教会了我研究历史的基本“技术方法”。