Answer: (秦 qín)
Analysis:
chūn hé qiū dōu bù rè （dǎ yī zì 打一字）
Neither spring nor autumn are hot (give one character)
春和秋都不热（打一字）
日（rì）和火（huǒ）都跟热（rè）有关，于是去掉，组成一个新字，秦（qín）。
日(rì) and 火(huǒ) are both related to 热 (rè), so they are removed to form a new character, 秦(qín).