Not left out at the start being outspoken (10)
I believe the answer is:
forthright
'outspoken' is the definition.
(I know that outspoken can be written as forthright)
'not left out at the start' is the wordplay.
'not left' becomes 'right' ('right' is the opposite to 'left').
'out' becomes 'forth' (I've seen this before).
'at the start' means one lot of letters go next to another.
'right' after 'forth' is 'FORTHRIGHT'.
'being' is the link.
(Other definitions for forthright that I've seen before include "Frank and uninhibited" , "Open" , "Straight-talking" , "Candid" , "Direct, outspoken" .)