Copper full of energy participating in country watch (8)
I believe the answer is:
spectate
'watch' is the definition.
(spectating is a kind of watching)
'copper full of energy participating in country' is the wordplay.
'copper' becomes 'pc'.
'full of' means one lot of letters goes inside another.
'energy' becomes 'e' (physics symbol as in E=mct).
'participating in' means one lot of letters goes inside another.
'country' becomes 'state' ('state' can be a synonym of 'country'**).
'pc' enclosing 'e' is 'pec'.
'pec' inserted into 'state' is 'SPECTATE'.
(Other definitions for spectate that I've seen before include "Perhaps enjoy sport" , "Watch (eg, a game)" , "Watch (a game, etc)" , "Be an onlooker" , "Look on (at a match)" .)