Drug of European that stops endless burping somehow (9)
I believe the answer is:
ibuprofen
'drug' is the definition.
(ibuprofen is a kind of drug)
'of european that stops endless burping somehow' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'that stops' indicates putting letters inside (stopping can mean blocking a gap).
'endless' means to remove the last letter.
'somehow' is an anagram indicator.
'of'+'e'='ofe'
'burping' with its final letter taken away is 'burpin'.
'burpin' is an anagram of 'ibuprn'.
'ofe' put inside 'ibuprn' is 'IBUPROFEN'.
(Other definitions for ibuprofen that I've seen before include "anaesthetic" , "Painkiller" , "Drug" , "Anti-inflammatory medicine" .)