楽句 is read as がっく (gakku) and means phrase.
がっく
gakku
がっき
musical instrument
がくふ
score
がくたい
band
がくだん
musical world
らくてんしゅぎ
optimism
らっかんしゅぎ
らくてんせいめいほけん
Rakuten Life Insurance
がくし
musician
らくてんしょうけん
Rakuten Securities
がくせつ
musical passage or section
がっきてん
musical instrument store
らくてんしゅぎしゃ
optimist