They're not in the front row when the game starts (5)
I believe the answer is:
pawns
'starts' is the definition.
The answer and definition can be both acts as well as being plural nouns.
Maybe there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for pawns that I've seen before include "The foot-soldiers in chess" , "Puts into hock" , "Chess pieces" , "Minor chessmen" , "made pledges" .)