Thin time acquiring Volume One’s opening? Good luck as you go (3,6)
I believe the answer is:
bon voyage
'opening? good luck as you go' is the definition.
I can't judge whether this defines the answer.
'thin time acquiring volume one's' is the wordplay.
'thin' becomes 'bony' (similar in meaning).
'time' becomes 'age' (an age is a period of time).
'acquiring' is an insertion indicator.
'volume one' becomes 'vo' (this might be a standard abbreviation which I don't know about).
'bony'+'age'='bonyage'
'bonyage' placed around 'vo' is 'BON VOYAGE'.
Can you help me to learn more?
(Other definitions for bon voyage that I've seen before include "Have a nice cruise, monsieur" , "Have a good journey - at sea" , "travel well!" , "Have a good trip - on the briny" .)