The term 'NOT AT ONE'S DESK' can be summarized as being AWAY from one's desk. This phrase is often used to describe someone who is not at their usual place of work, such as an office or desk. It could mean that the person is on a break, out for lunch, or even on vacation. It could also mean that the person is working remotely, such as from home or another location. The crossword solution for this term is 'AWAY', which is a four-letter word.