Five accessing a hollow entrance (6)
I believe the answer is:
advent
'entrance' is the definition.
(both can mean the arrival of something)
'five accessing a hollow' is the wordplay.
I cannot really understand how this works, but
'five' could be 'v' (roman numeral) and 'v' is present in the answer.
'a' is within the answer.
'hollow' could be 'dent' (I've seen this before) and 'dent' is found in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for advent that I've seen before include "It's a-coming in December!" , "Christian season" , "when the Church year begins" , "Coming (of Christmas)" , "observed by Christian church" .)