Huge distance run in space-travelling (6)
I believe the answer is:
parsec
'huge distance' is the definition.
'run in space-travelling' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'travelling' is an anagram indicator.
'r'+'space'='rspace'
'rspace' with letters rearranged gives 'PARSEC'.
(Other definitions for parsec that I've seen before include "Unit for measurement of distance of stars" , "3.26 light years" , "Unit of interstellar distance" , "Unit of distance in space" , "Immense unit of distance" .)