Ambitious German discarded drug (7)
I believe the answer is:
aspirin
'drug' is the definition.
(aspirin is a kind of drug)
'ambitious german discarded' is the wordplay.
'ambitious' becomes 'aspiring' ('aspiring' can be similar in meaning to 'ambitious').
'german' becomes 'g' (abbreviation).
'discarded' suggests deleting specific letters.
'aspiring' with 'g' taken away is 'ASPIRIN'.
(Other definitions for aspirin that I've seen before include "Mild pain-killing drug" , "number" , "Common pain tablet" , "Analgesic over in Paris" , "Pain-relieving drug made in Paris" .)