Second-in-command forbidding stink (5)
I believe the answer is:
odour
'stink' is the definition.
(I've seen this before)
'second-in-command forbidding' is the wordplay.
'second in-command' becomes 'o' (2nd letter of 'command').
'forbidding' becomes 'dour' (I've seen this before).
'o'+'dour'='ODOUR'
(Other definitions for odour that I've seen before include "Distinctive smell" , "Smell; repute" , "Aroma or fragrance" , "reputation" , "Small, aroma" .)