One yet to be adopted by the German company making spirits (9)
I believe the answer is:
distiller
'company making spirits' is the definition.
(a company that distils alcohol)
'one yet to be adopted by the german' is the wordplay.
'one' becomes 'i' (Roman numeral).
'yet' becomes 'still' (synonyms).
'to be adopted by' is an insertion indicator (I've seen this in other clues).
'the german' becomes 'der' ('the' in German).
'i'+'still'='istill'
'istill' going inside 'der' is 'DISTILLER'.
(Other definitions for distiller that I've seen before include "Eg, whisky producer" , "One providing strong drink" , "a person of strong spirit" , "spirited person?" , "Producer of spirits" .)