Group of musicians reek and set off soldier (9)
I believe the answer is:
musketeer
'soldier' is the definition.
(I know that musketeer is a type of foot soldier)
'group of musicians reek and set off' is the wordplay.
'group of musicians' becomes 'mu' (I can't justify this - if you can you should believe this answer much more).
'and' is a charade indicator (letters next to each other).
'off' indicates anagramming the letters.
'reek' after 'set' is 'setreek'.
'setreek' anagrammed gives 'sketeer'.
'mu'+'sketeer'='MUSKETEER'
Can you help me to learn more?
(Other definitions for musketeer that I've seen before include "Household troop member" , "Historical soldier" , "Fighter" , "One of Dumas's three" , "One of Dumas' trio with guns" .)