Crossword Genius

Criminals one may be as thick as (7)

Ross

I believe the answer is:

thieves

I'm a little stuck... Click here to teach me more about this clue!

'criminals' is the definition.
(thief is a kind of criminal)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for thieves that I've seen before include "People who steal" , "they whip things" , "Crooks" , "Stealers" , "They pinch" .)

I've seen this clue in The Mirror.
Want a hint initially instead of a full solution? Install my app