Trumpet-bearer at the front calling Russians to assemble (9)
I believe the answer is:
narcissus
'trumpet-bearer' is the definition.
'the front calling russians to assemble' is the wordplay.
'the front' indicates taking the first letters.
'to assemble' is an anagram indicator.
The initial letter of 'calling' is 'c'.
'c'+'russians'='crussians'
'crussians' is an anagram of 'NARCISSUS'.
'at' acts as a link.
(Other definitions for narcissus that I've seen before include "Daffodil-like bulb" , "Mythical egotist" , "Variety of daffodil" , "Legendary egotist" , "Flower; Gk. youth in love with reflection" .)