The phrase "one's primary job" refers to the main or most important work or occupation that someone has. It is the job that takes up most of their time, and often the one that provides them with the majority of their income. Full definition
Primary job responsibilities include assessing health condition, offering advice, helping clients formulate health goals, and establishing treatment plans. (jobhero.com)
Primary job duties include reliability, friendly, team - orientation and honesty, etc.. (topjobapplications.com)
Just as the name implies, debt collectors are individuals or businesses whose primary job is to collect debts. (natlbankruptcy.com)