Bad pirate provided opening shot (8)
I believe the answer is:
aperitif
'opening shot' is the definition.
(alcohol drunk at the start of a meal)
'bad pirate provided' is the wordplay.
'bad' is an anagram indicator.
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'pirate' is an anagram of 'aperit'.
'aperit'+'if'='APERITIF'
(Other definitions for aperitif that I've seen before include "Drink stimulating the appetite" , "Alcoholic drink to whet the appetite" , "Alcoholic beverage as an appetiser" , "it leads to blow-out" , "An alcoholic drink before dinner, an appetiser" .)