Public availability of back numbers (5)
I believe the answer is:
civic
This clue could be a double definition.
'public' is the first definition.
(thesaurus)
'availability of back numbers' is the second definition.
'civic' can be an answer for 'numbers' (I have seen 'Numbers of Romans' mean 'civic' so perhaps 'numbers' could also mean 'civic'). I am not certain of the 'availability of back' bit.
Can you help me to learn more?
(Other definitions for civic that I've seen before include "concerned with town administration" , "Relating to a city/town" , "Relating to citizens" , "Relating to a town/city" , "Relating or belonging to a city" .)