Treading the boards, one leg after another? (2,5)
I believe the answer is:
on-stage
'treading the boards' is the definition.
(I've seen this before)
'one leg after another?' is the wordplay.
'one leg' becomes 'on' (cricket term, fielding positions).
'after' is a charade indicator (letters next to each other).
'another?' becomes 'stage' (I am not sure about this - if you are sure you should believe this answer much more).
'on'+'stage'='ON-STAGE'
Can you help me to learn more?
(Another definition for on-stage that I've seen is " Like some performances".)