The most common and most likely answer to this crossword clue is the 8 letter word RAINBOWS
I've seen this crossword clue in The Guardian
R
A
I
N
B
O
W
S
More clues leading to the result RAINBOWS
Buddy explains!
The straight part
We know that "Spectrums" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spectrums = rainbows.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 RAINBOWS mean?
RAINBOWS noun- A multicoloured arch in the sky, produced by prismatic refraction of light within droplets of rain in the air.
- Any prismatic refraction of light showing a spectrum of colours.
- (often used with “of”) A wide assortment; a varied multitude.
- An illusion, mirage.
- A curveball, particularly a slow one.
- In Texas hold 'em or Omaha hold 'em, a flop that contains three different suits.
- Rainbow trout.
- To brighten with, or as with, a rainbow; to pattern with the colours of the rainbow.
- To take the appearance of a rainbow.