Are such workers too careless for regular employment? (6)
I believe the answer is:
casual
'are' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives sometimes define each other.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for casual that I've seen before include "Informal, dress say" , "Informal or happening by chance" , "Informal like clothes" , "Of clothes, not formal" , "Informal or cursory" .)