Knightly combat judge originally saw during excursion (8)
I believe the answer is:
jousting
'knightly combat' is the definition.
(as in medieval jousting)
'judge originally saw during excursion' is the wordplay.
'judge' becomes 'j' (abbreviation for judge).
'originally' indicates taking the first letters.
'during' is an insertion indicator.
'excursion' becomes 'outing' (synonyms).
The initial letter of 'saw' is 's'.
's' inserted inside 'outing' is 'ousting'.
'j'+'ousting'='JOUSTING'
(Other definitions for jousting that I've seen before include "Fighting on horseback in a tournament" , "tilting!" .)