Mark has performed outside shed (7)
I believe the answer is:
discard
'shed' is the definition.
(I've seen this before)
'mark has performed outside' is the wordplay.
'mark has' becomes 'scar' (I am not sure about this - if you are sure you should believe this answer much more).
'performed' becomes 'did' ('do' can be a synonym of 'perform').
'outside' indicates putting letters inside.
'scar' inserted inside 'did' is 'DISCARD'.
Can you help me to learn more?
(Other definitions for discard that I've seen before include "bin" , "Throw away or cast off" , "Abandon" , "Get rid of" , "Jettison" .)