Strange tales about firm that once flavoured beer (7)
I believe the answer is:
alecost
'once flavoured beer' is the definition.
(aromatic plant once used in drinks and medicine)
'strange tales about firm' is the wordplay.
'strange' indicates an anagram.
'about' means one lot of letters goes inside another.
'firm' becomes 'co' (a firm is a company).
'tales' is an anagram of 'alest'.
'alest' placed around 'co' is 'ALECOST'.
'that' is the link.
(Other definitions for alecost that I've seen before include "Herb" , "used to provide flavouring for beer" , "plant" .)