Group of musicians -- see men playing around British Legion (8)
I believe the answer is:
ensemble
'group of musicians' is the definition.
(I've seen this before)
'see men playing around british legion' is the wordplay.
'playing' indicates an anagram.
'around' means one lot of letters goes inside another.
'british legion' becomes 'bl' (abbreviation).
'see'+'men'='seemen'
'seemen' is an anagram of 'enseme'.
'enseme' going around 'bl' is 'ENSEMBLE'.
(Other definitions for ensemble that I've seen before include "Musical company" , "Group of musicians or a co-ordinated outfit" , "chamber group?" , "Group of musicians or co-ordinated clothes" , "Complete outfit - group of musicians" .)