The most common and most likely answer to this crossword clue is the 5 letter word CLOUD
I've seen this crossword clue in The Guardian
C
L
O
U
D
More clues leading to the result CLOUD
- Ideal location to film, perhaps, with soft light
- Obscure college gaudy
- What a wandering poet thought lacking company is obscure
- Dim, cold and thundering
- Almost hit daughter coming out of one’s shower?
- Obscure bird seen over dock — pie in the sky?
- Obscure sort of clock light is an escape from reality
- Dull spot in college gaudy
- Gloom when 17 symbolically upset couple
- Bananas put in dull bag in fanciful place
Buddy explains!

The straight part
We know that "Dim" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dim = cloud.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 CLOUD mean?
CLOUD noun- A rock; boulder; a hill.
- A visible mass of water droplets suspended in the air.
- Any mass of dust, steam or smoke resembling such a mass.
- Anything which makes things foggy or gloomy.
- Anything unsubstantial.
- A dark spot on a lighter material or background.
- A group or swarm, especially suspended above the ground or flying.
- An elliptical shape or symbol whose outline is a series of semicircles, supposed to resemble a cloud.
- (with "the") The Internet, regarded as an abstract amorphous omnipresent space for processing and storage, the focus of cloud computing.
- A negative or foreboding aspect of something positive: see every cloud has a silver lining or every silver lining has a cloud.
- Crystal methamphetamine.
- A large, loosely-knitted headscarf worn by women.
- To become foggy or gloomy, or obscured from sight.
- To overspread or hide with a cloud or clouds.
- To make obscure.
- To make less acute or perceptive.
- To make gloomy or sullen.
- To blacken; to sully; to stain; to tarnish (reputation or character).
- To mark with, or darken in, veins or sports; to variegate with colors.
- To become marked, darkened or variegated in this way.