How can a door be this? (4)
I believe the answer is:
ajar
'door be this?' is the definition.
The definition suggests a singular noun but the answer is not.
'how can a' is the wordplay.
I cannot quite see how this works, but
'a' is present in the answer.
The remaining letters 'jar' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ajar that I've seen before include "Partly open" , "It's nearly open" , "A little bit open, like door" , "Not to answer" , "Mourn" .)