sport

AnneはAvonleaから離れた学校生活でホームシックにかかっています。　そこに現れたJosieの台詞です。
Ah, I guessed likely Marilla'd load you up with cake. That's why I called round. Otherwise I'd have gone to the park to hear the band play with Frank Stockley. He boards same place as I do, and he's a sport.
以前 "sport" の名詞用法で "(biology) an organism that has characteristics resulting from chromosomal alteration" の意味の例がありましたがここではもちろんそんな意味ではないでしょう。　スポーツマンの意味かなとも思いますが、何となくここでは "sport" に別の意味があるような気がします。　辞書を見ると色々な意味があります。
・Dictionary.com:
9. a sportsman.
10. Informal. a person who behaves in a sportsmanlike, fair, or admirable manner; an accommodating person: He was a sport and took his defeat well.
11. Informal. a person who is interested in sports as an occasion for gambling; gambler.
12. Informal. a flashy person; one who wears showy clothes, affects smart manners, pursues pleasurable pastimes, or the like; a bon vivant.
別の辞書も見ます。
・American Herritage Dictionary:
f. Informal A pleasant companion: was a real sport during the trip.
g. A person who lives a jolly, extravagant life.
多分このf.の意味（A pleasant companion）で解釈するのが一番自然の気がします。