Desirous to make a flight on fantastic fuel! (7)
I believe the answer is:
hopeful
'desirous' is the definition.
(thesaurus)
'a flight on fantastic fuel' is the wordplay.
'a flight on' becomes 'hop' (I can't explain this - if you can you should believe this answer much more).
'fantastic' is an anagram indicator (a fantastic or improbable ordering of the letters).
'fuel' is an anagram of 'eful'.
'hop'+'eful'='HOPEFUL'
'to make' acts as a link.
Can you help me to learn more?
(Other definitions for hopeful that I've seen before include "One wishing to succeed" , "Promising success" , "Prospect" , "Wannabe" , "Optimistic, expectant" .)