The most common and most likely answer to this crossword clue is the 7 letter word DETECTS
I've seen this crossword clue in Independent
D
E
T
E
C
T
S
More clues leading to the result DETECTS
Buddy explains!

The straight part
We know that "spots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spots = detects.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 DETECTS mean?
DETECTS verb- To discover or find by careful search, examination, or probing