Assuming that the italicized clause is "when the hairbrush pulled her long curls" it is an adverb clause
Explanation:
An adverb clause is an individual adverb or a group of words that is going to be connected to the main sentence by an adverb, this specific example is using the subordinating conjunction "when" that is connecting the subordinated clause that is giving extra information to the main sentence to create a full adverb clause.
