Workers officially organised races, one for all on staff (5)
I believe the answer is:
tutti
'for all on staff' is the definition.
(Italian for 'all' - used on musical staff)
'workers officially organised races one' is the wordplay.
'workers officially organised' becomes 'TU' (trade union).
'races' becomes 'tt' (Isle of Man Tourist Trophy races).
'one' becomes 'i' (Roman numeral).
'tu'+'tt'+'i'='TUTTI'
(Other definitions for tutti that I've seen before include "Everyone join in (mus.)" , "All (stage direction)" , "(Of an orchestra) all to play together" , "All performers (mus.)" , "Piece together" .)