Speculation is in the wind about medical man (6)
I believe the answer is:
gamble
'speculation' is the definition.
(I know that gamble is a type of speculation)
'the wind about medical man' is the wordplay.
'the wind' becomes 'gale' (gale is a kind of wind).
'about' is an insertion indicator.
'medical man' becomes 'MB' (someone with a Bachelor of Medicine degree).
'gale' enclosing 'mb' is 'GAMBLE'.
'is in' is the link.
(Other definitions for gamble that I've seen before include "back" , "Take a chance, speculate" , "Take risks" , "Bet money" , "Bet -- Procter's partner" .)