Fortunate adult wary, not having succeeded initially (10)
I believe the answer is:
auspicious
'fortunate' is the definition.
(similar in meaning)
'adult wary not having succeeded initially' is the wordplay.
I cannot really understand how this works, but
'adult' could be 'a' (abbreviation) and 'a' is present in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
'succeeded' could be 's' (genealogical abbreviation) and 's' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for auspicious that I've seen before include "Promising" , "Favourable" , "Rosy" .)