Sentence:  Through over-practice of Balakiref's "Islamey" and Liszt's "Don Juan" Fantasia, he temporarily lost the use of his right hand. He regained it after a time, but it was during this period of <WSD>single-handedness</WSD> that he wrote the well-known “Prelude and Nocturne for the left hand only”, as well as a left-handed concert-paraphrase of a Strauss waltz, which has never been published. 
Meaning of the word marked with <WSD> tags:  The quality of having or involving the use of only one hand.