Noxious airline fuel spilt next to Bristol's terminal (7)
I believe the answer is:
baleful
'noxious' is the definition.
(thesaurus)
'airline fuel spilt next to bristol's terminal' is the wordplay.
'airline' becomes 'BA' (British Airways).
'spilt' indicates an anagram.
'next to' is a charade indicator (letters next to each other).
'terminal' says to take the final letters (the final or terminal letter).
The last letter of 'bristol' is 'l'.
'fuel' with letters rearranged gives 'lefu'.
'ba'+'lefu'+'l'='BALEFUL'
(Other definitions for baleful that I've seen before include "Menacing - gloomy" , "Malevolent" , "Of look, menacing or destructive" , "Menacing - vindictive" , "Of evil influence" .)