Awfully nice specialist about to get fiancee finally pregnant (8)
I believe the answer is:
enceinte
'pregnant' is the definition.
(similar in meaning)
'awfully nice specialist about to get fiancee finally' is the wordplay.
'awfully' indicates an anagram.
'specialist' becomes 'ent' (Ear, Nose and Throat specialist).
'about' indicates putting letters inside.
'to get' says to put letters next to each other.
'finally' suggests the final letters.
The final letter of 'fiancee' is 'e'.
'nice' with letters rearranged gives 'cein'.
'cein' inserted within 'ent' is 'enceint'.
'enceint'+'e'='ENCEINTE'
(Other definitions for enceinte that I've seen before include "enclosure" , "Like a woman expecting" , "some fortification" .)