Advantage gained by Dutch champion during preliminary race (4,5)
I believe the answer is:
head start
'advantage' is the definition.
(head start is a kind of advantage)
'dutch champion during preliminary race' is the wordplay.
'dutch' becomes 'd' (common abbreviation).
'champion' becomes 'star' (both can mean a popular or successful person).
'during' is an insertion indicator.
'preliminary race' becomes 'heat' (I've seen this in another clue).
'd'+'star'='dstar'
'dstar' going into 'heat' is 'HEAD START'.
'gained by' acts as a link.
(Other definitions for head start that I've seen before include "'The advantage of beginning ahead of others (4,5)'" , "Advantage gained by beginning early" , "Substantial initial advantage" , "Boost?" , "A good beginning using one's loaf" .)