The most common and most likely answer to this crossword clue is the 4 plus 4 letter word LAVA LAMP
I've seen this crossword clue in The Daily Telegraph
L
A
V
A
L
A
M
P
More clues leading to the result LAVA LAMP
- Privy, in the style of backbencher getting illumination with motion
- Former French PM, and member, plugging in a decorative novelty item
- Hot rock and roll orchestra, rhythm group finally part of the sixties scene
- Hippie turn on?
- French PM and MP installing a decorative object in the House?
- A member on line by toilet area gets light
Buddy explains!

The straight part
We know that "light" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case light = lava lamp.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.