False fuel supply, which is scandalous (8)
I believe the answer is:
shameful
'is scandalous' is the definition.
(I've seen this in another clue)
'false fuel supply' is the wordplay.
'false' becomes 'sham' (sham means fake or pretend).
'supply' is an anagram indicator (in a supple way).
'fuel' with letters rearranged gives 'eful'.
'sham'+'eful'='SHAMEFUL'
'which' is the link.
(Other definitions for shameful that I've seen before include "Reprehensible" , "scandalous!" , "Embarrassing" , "Ignoble, shocking" , "Disgraceful" .)