Bet doctor is inside storm (6)
I believe the answer is:
'bet' is the definition.
(I've seen this before)
'doctor is inside storm' is the wordplay.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'is inside' means one lot of letters goes inside another.
'storm' becomes 'gale' (I've seen this before).
'mb' put within 'gale' is 'GAMBLE'.
(Other definitions for gamble that I've seen before include "Bet money" , "Make a bet" , "Bet -- Procter's partner" , "Run a risk" , "Flutter" .)