The most common and most likely answer to this crossword clue is the 6 letter word SPYING
I've seen this crossword clue in The Daily Telegraph
S
P
Y
I
N
G
More clues leading to the result SPYING
- Working with intelligence, start to plant yard with grass border
- Spotting pony with leg hidden in grass
- Confess, accepting case of perjury – it’s intelligence work
- Spotting James Bond’s craft
- 16's speciality: primarily Stolichnaya, Perrier, finally Tanquerary gin. Stir.
- Noticing outline of prey hidden in grass
Buddy explains!

The straight part
We know that "Noticing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case noticing = spying.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 SPYING mean?
SPYING verb- To act as a spy.
- To spot; to catch sight of.
- To search narrowly; to scrutinize.
- To explore; to see; to view; inspect and examine secretly, as a country.
- Espionage