London district heralding extremely inventive musician (5)
I believe the answer is:
bowie
'musician' is the definition.
(David Bowie, 1947-2016)
'london district heralding extremely inventive' is the wordplay.
'london district' becomes 'Bow' (area of London).
'heralding' says to put letters next to each other (some letters come before others).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'inventive' with its centre removed is 'ie'.
'bow'+'ie'='BOWIE'
(Other definitions for bowie that I've seen before include "Art rocker David" , "Rock-based chameleon" , "Dagger-knife" , "David --, rock singer/songwriter" , "David --, singer" .)