Are these 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 occasionally define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for casual that I've seen before include "Careless; unsystematic" , "Relaxed; accidental" , "Informal, not methodical" , "displaying lack of commitment" , "Relaxed, unconcerned" .)