A door's opening, calling for entrance (9)
I believe the answer is:
admission
'entrance' is the definition.
(admission is a kind of entrance)
'a door's opening calling' is the wordplay.
'opening' suggests taking the first letters.
'calling' becomes 'mission' (I've seen this before).
The initial letter of 'doors' is 'd'.
'a'+'d'+'mission'='ADMISSION'
'for' acts as a link.
(Other definitions for admission that I've seen before include "Acknowledgment of crime" , "Letting in - letting out" , "guilty plea, perhaps" , "for which one may be charged" , "Acknowledgment of the truth of something" .)