Argoru III (1971) for flute is the third in a series of eight solo works for various instruments, the term ''argoru'' being a word from the Ghanaian Twi language meaning ''to play'' (itself a pun). The work is in one short movement. Quicksilver runs and leaps alternate with cantabile moments like light falling through trees in a forest. The work at times seems to sound as if the flutist herself were creating the piece in a moment of inspired improvisation. The composer in fact says his intention was to ''create a virtuosic tribute to a great flutist, allowing the piece to sound like her own personal statement.'' To play ''Argoru'' with proper joy and abandon requires a flutist of great virtuosity. Such a player is Sara Vargas-Barritt for whom Mr. Singleton composed ''Argoru III'' and who premiered it on 24 May 1971 in Sprague Memorial Hall, New Haven, Connecticut, where the two were fellow Yale graduates. - Carman Moore