When a team's out for a bit of training, it means progress (6)
I believe the answer is:
stride
'progress' is the definition.
(I know that stride is a type of progress)
'when a team's out' is the wordplay.
'when' becomes 'tr' (I can't justify this - if you can you should believe this answer much more).
'a team' becomes 'side' (both can mean a sports team).
'out' is an insertion indicator.
'tr' inserted into 'side' is 'STRIDE'.
'for a bit of training it means' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for stride that I've seen before include "Step out energetically" , "Extended footstep" , "A big step forward" , "use your legs!" , "Move with long steps" .)