Group transporting tonne (5)
I believe the answer is:
nonet
'group' is the definition.
(group of nine musicians)
'transporting tonne' is the wordplay.
'transporting' is an anagram indicator (I've seen 'transport' mean this (letters are transported elsewhere)).
'tonne' anagrammed gives 'NONET'.
(Other definitions for nonet that I've seen before include "Tonne (anag.); music for a group" , "Tenon (anag.)" , "group composition" , "Band of nine?" , "small band" .)