The most common and most likely answer to this crossword clue is the 6 letter word PHOTON
I've seen this crossword clue in The Guardian
P
H
O
T
O
N
More clues leading to the result PHOTON
- Name on picture provides some illumination
- Light particle is still radiation in the end
- Snapshot taken with night starting? There’s minimal light
- Physicist initially well-informed about light particle
- Quietly heading for home, finally to depart on light carrier
- Quiet fashion house included something very small
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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 PHOTON mean?
PHOTON noun- The quantum of light and other electromagnetic energy, regarded as a discrete particle having zero rest mass, no electric charge, and an indefinitely long lifetime. It is a gauge boson.