Budding compiler returning: eager, vacuous fellow (8)
I believe the answer is:
emergent
'budding' is the definition.
(I've seen this in another clue)
'compiler returning eager vacuous fellow' is the wordplay.
'compiler' becomes 'me' (the person who is writing these clues).
'returning' shows that the letters should be reversed in order.
'vacuous' says to hollow out the word (remove centre letters).
'fellow' becomes 'gent' (synonyms).
'eager' with its centre taken out is 'er'.
'me' written backwards gives 'em'.
'em'+'er'+'gent'='EMERGENT'
(Other definitions for emergent that I've seen before include "coming into view" , "Greet men (anag) - developing" , "Breaking" , "Coming into existence" , "Rising" .)