Many, I learn, ordered a soft drink (7)
I believe the answer is:
mineral
'a soft drink' is the definition.
(I've seen this before)
'many i learn ordered' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'ordered' indicates an anagram.
'i'+'learn'='ilearn'
'ilearn' is an anagram of 'ineral'.
'm'+'ineral'='MINERAL'
(Other definitions for mineral that I've seen before include "Made from inorganic matter" , "Type of spring water" , "ore, possibly" , "Substance that is (usually) inorganic" , "Neither animal nor vegetable" .)