Old store of brine that fermented (5,4)
I believe the answer is:
tithe barn
'old store' is the definition.
'tithe barn' can be an answer for 'store' (I have seen 'Rural store' mean 'tithe barn' so perhaps 'store' could also mean 'tithe barn'). I am not certain of the 'old' bit.
'brine that fermented' is the wordplay.
'fermented' indicates an anagram.
'brine'+'that'='brinethat'
'brinethat' is an anagram of 'TITHE-BARN'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for tithe barn that I've seen before include "Church tax store" , "historic building?" , "somewhere in farm" , "tax shelter?" , "Where some taxes are collected" .)