The most common and most likely answer to this crossword clue is the 5 letter word IDLED
I've seen this crossword clue in The Daily Telegraph
I
D
L
E
D
More clues leading to the result IDLED
- Ticked over five hundred large — that is five hundred— boxes!
- Turned over papers brought to light
- Ran out of gear – Bluth had been in front
- I’d gone first, and just ran
- Moved furtively heading off, but didn’t do anything
- Turned over papers by the light
- One day, provoked, did nothing
- Chalmie had been first and did nothing
- Sample of dolcelatte where you’d find it served up? Wasn’t engaged
- Guided by instinct, didn’t do much
Buddy explains!

The straight part
We know that "watched others working" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case watched others working = idled.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does IDLED mean?
IDLED verb- To spend in idleness; to waste; to consume.
- To lose or spend time doing nothing, or without being employed in business.
- Of an engine: to run at a slow speed, or out of gear; to tick over.