Distance competed over at some stage (5)
I believe the answer is:
range
'distance' is the definition.
(I've seen this in another clue)
'competed over at some stage' is the wordplay.
'competed' becomes 'ran' (running is a kind of competing).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'at some stage' becomes 'ge' (I can't justify this - if you can you should give a lot more credence to this answer).
'ran'+'ge'='RANGE'
Can you help me to learn more?
(Other definitions for range that I've seen before include "Variation within limits" , "bounds" , "practise shooting here" , "Oven" , "Shooting area - group of mountains" .)