Put out, as items that are completed may be (6,3)
I believe the answer is:
ticked off
'items that are completed may be' is the definition.
I can't judge whether this defines the answer.
'put out' is the wordplay.
'put' becomes 'ticked' (I can't explain this - if you can you should give a lot more credence to this answer).
'out' becomes 'off' (I've seen this before).
'ticked'+'off'='TICKED OFF'
'as' is the link.
Can you help me to learn more?
(Other definitions for ticked off that I've seen before include "checked the completion" , "Reprimanded" , "roasted" , "Scolded" , "Marked present" .)