They employ strange ruses (5)
I believe the answer is:
users
'they employ' is the definition.
(I've seen this in another clue)
'strange ruses' is the wordplay.
'strange' indicates an anagram.
'ruses' anagrammed gives 'USERS'.
(Other definitions for users that I've seen before include "Customers" , "Utilisers" , "subscribers" , "Operators" , "People with a drug habit" .)