请问，为什么：

「听清楚」不说 「听得清楚」

但是

「学习得很好」不说 「学习很好」

听清楚 emphasizes the action itself. For instance, " 你要听清楚老师的要求啊。 You must understand the teacher's requirement. ( You must fulfil the action of hearing and understanding ).
听得清楚 emphasizes the result of listening. For instance, " 你讲的话我听得很清楚。” I heard what you had said very clearly. （ Focus on the result ) .

很好 is an adj. which can be used as a completement of the action . It cannot be used to modify the verb " 学习" 。 If 学习 is a noun, 很好should be put before . 这是一种很好的学习。 This is a kind of good study. 一种 is a quantifier .