What a heavenly garden the dentist has! (4)
I believe the answer is:
eden
'what a heavenly garden' is the definition.
(I've seen this in another clue)
'the dentist has' is the wordplay.
'has' indicates a hidden word.
'EDEN' is hidden within 'the dentist'.
(Other definitions for eden that I've seen before include "Former British PM - unspoilt paradise" , "Delightful place" , "Badly need the garden" , "Paradise - ex-prime minister" , "Adam and Eve's 19" .)