Excellent commando principally involved in each uprising (3)
I believe the answer is:
ace
'excellent' is the definition.
(ace can informally mean very good)
'commando principally involved in each uprising' is the wordplay.
'principally' says to take the initial letters.
'involved in' indicates putting letters inside.
'each' becomes 'ea' (abbreviation).
'uprising' is a reversal indicator.
The first letter of 'commando' is 'c'.
'c' placed within 'ea' is 'eca'.
'eca' back-to-front is 'ACE'.
(Other definitions for ace that I've seen before include "Card with a single pip" , "hotshot" , "One in a suit" , "Playing card with single spot" , "rare driving result?" .)