Ale and prawn cocktail? It could kill you (8)
I believe the answer is:
warplane
'it could kill you' is the definition.
(plane used to attack people in war)
'ale and prawn cocktail?' is the wordplay.
'and' means one lot of letters go next to another.
'cocktail?' indicates anagramming the letters (I've seen 'cocktail' mean this).
'ale' put after 'prawn' is 'prawnale'.
'prawnale' is an anagram of 'WARPLANE'.
(Other definitions for warplane that I've seen before include "Military aircraft" , "Lancaster, perhaps" , "Aircraft for use in battle" , "Spitfire, for example" , "Such as Spitfire or Typhoon" .)