Adverbs refer to the words which modify the verb, adjectives or adverbs, expressing a relation of a cause, time, place and so forth.
Whereas, an adverb clause refers to the group of words which works as an adverb. An adverb clause begins with the subordinating conjunction such as if, although, because and so forth. Lastly, it includes subject and predicate.
Hence, in the sentence, " When you obey your parents, you please the lord.",
Adverb clause is- When you obey your parents.
Subordinating conjunction is- When.
The word modified is- Please.