After school, we all had a foot race.
かけっくらで一番になったよ!
I came first in the sprint!
Rare kanji spelling; the standard word for 'foot race' is かけっこ.
Variant kanji spelling; even rarer than 駆けっ競.
A colloquial form of 駆け競べ, “running contest,” with contraction and gemination in the sequence かけくらべ.