Shown, old Scot in action (8)
I believe the answer is:
depicted
'shown' is the definition.
('depict' can be a synonym of 'show')
'old scot in action' is the wordplay.
'old scot' becomes 'Pict' (ancient people in Scotland during Roman times).
'in' is an insertion indicator.
'action' becomes 'deed' (deed is a kind of action).
'pict' going within 'deed' is 'DEPICTED'.
(Other definitions for depicted that I've seen before include "Described or portrayed in words" , "Shown" .)