Just leaving worker lacking courtesy (7)
I believe the answer is:
offhand
'just leaving worker lacking courtesy' is the definition.
I can't tell whether this definition defines the answer.
'just leaving worker' is the wordplay.
'just leaving' becomes 'off' (as in 'I'm off'. I am not sure about the 'just' bit.).
'worker' becomes 'hand' (hand is a kind of worker).
'off'+'hand'='OFFHAND'
Can you help me to learn more?
(Other definitions for offhand that I've seen before include "Casually thoughtless or inconsiderate" , "Ungraciously curt" , "Without thought" , "Without consideration" , "Casual or curt, like discarded glove?" .)