Cracked, as a door
I believe the answer is:
ajar
'cracked as a door' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ajar that I've seen before include "Raja (anag.)" , "Fractionally open" , "(Door) to, not shut" , "A litle bit open" , "not slammed shut" .)