The most common and most likely answer to this crossword clue is the 5 letter word SIDLE
I've seen this crossword clue in The Guardian
S
I
D
L
E
More clues leading to the result SIDLE
- Edge of wheel discovered to have shrivelled up
- Sneak unused to follow society
- Line occupying edge to edge
- Sneakily move line, splitting team
- Ass indulges regularly - make oblique movement
- School head’s vain — creep!
- Creep in small lounge
- Sneak around in novel disguise
- Walk furtively in square with nothing to do
- Try to walk like a crab and slide about
Buddy explains!

The straight part
We know that "Creep" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case creep = sidle.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 SIDLE mean?
SIDLE noun- An act of sidling.
- To (cause something to) move sideways.
- In the intransitive sense often followed by up: to (cause something to) advance in a coy, furtive, or unobtrusive manner.