The most common and most likely answer to this crossword clue is the 5 letter word CRAWL
I've seen this crossword clue in The Times
C
R
A
W
L
More clues leading to the result CRAWL
- Fresh chlorine put round something used at the pool
- Fawn starts to cautiously run along wooded lane
- Hard in centre of clubland to get a dance for oldies
- Such as keeps lobster fresh in Sri Lanka
- Left on stomach move thus?
- Stroke head of cat on green overlooking lake
- Move slowly, freezing in empty cell
- Stroke fawn
- Stroke head and tail of cougar with tool
- What swimmers may do to snail?
Buddy explains!

The straight part
We know that "Move slowly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case move slowly = crawl.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 CRAWL mean?
CRAWL noun- The act of moving slowly on hands and knees etc, or with frequent stops.
- A rapid swimming stroke with alternate overarm strokes and a fluttering kick.
- A very slow pace.
- A piece of horizontally or vertically scrolling text overlaid on the main image.
- To creep; to move slowly on hands and knees, or by dragging the body along the ground.
- To move forward slowly, with frequent stops.
- To act in a servile manner.
- (with "with") See crawl with.
- To feel a swarming sensation.
- To swim using the crawl stroke.
- To move over an area on hands and knees.
- To visit while becoming inebriated.
- To visit files or web sites in order to index them for searching.
- A pen or enclosure of stakes and hurdles for holding fish.