The most common and most likely answer to this crossword clue is the 9 letter word REFLECTOR
I've seen this crossword clue in The Times
R
E
F
L
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More clues leading to the result REFLECTOR
Buddy explains!
The straight part
We know that "glower" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case glower = reflector.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 REFLECTOR mean?
REFLECTOR noun- Something which reflects heat, light or sound, especially something having a reflecting surface.
- A reflecting telescope.
- A small, often red, reflecting disk on the rear of a vehicle or bicycle that reflects the headlights of other vehicles.
- A safety reflector.
- One who reflects on something; one who thinks or considers at length.