Concerned with new blunder, knocked over drink (7)
I believe the answer is:
pilsner
'drink' is the definition.
(pilsner is a kind of drink)
'concerned with new blunder knocked over' is the wordplay.
'concerned with' becomes 're' (re can mean regarding, concerning).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'blunder' becomes 'slip' (slip is a kind of blunder).
'knocked over' says the letters should be written backwards.
're'+'n'+'slip'='renslip'
'renslip' written backwards gives 'PILSNER'.
(Other definitions for pilsner that I've seen before include "Czech beer" , "drink" , "alcohol" , "Type of lager" , "Bar tab might include this" .)