The most common and most likely answer to this crossword clue is the 6 letter word ESPIAL
E
S
P
I
A
L
More clues leading to the result ESPIAL
- I must stop careless lapse being spotted
- Mistake overturned without a single observation
- Observation of shortcoming upset one getting caught
- Recurrent failure? I interposed observation
- Observation from London area about one in China?
- Observation — I will be trapped by error, getting knocked back
- Cut off paisley pants making old-fashioned sight
- One involved in slip up makes observation
- Slip back over island to make observation
- Looking back, negligence stopped patient's heart
Buddy explains!

The straight part
We know that "Observation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case observation = espial.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 ESPIAL mean?
ESPIAL noun- Act of noticing or observing.
- The fact of noticing or observing; a discovery.
- A spy; a scout.