Acting? Working on coach (2,5)
I believe the answer is:
on stage
'acting?' is the definition.
(I've seen this before)
'working on coach' is the wordplay.
'working' becomes 'on' (e.g. a machine is working or on).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'coach' becomes 'stage' (stagecoach).
'on'+'stage'='ON-STAGE'
(Other definitions for on stage that I've seen before include "Acting" , "like passengers in Wild West" , "for an audience to watch?" , "in front of a audience" , "performance" .)