Slippery customer having brief look around (3)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
eel
'slippery customer' is the definition.
(eel can mean a slippery person)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for eel that I've seen before include "elusive person" , "Fish in the Lee?" , "slipper" , "Slippery type" , "Snakelike fish" .)