The piece
Between two fast movements in C major, Clementi slips in an Andante in F major, in triple time, built on one simple idea: a melody in long notes carried by eighth-note triplet arpeggios in the left hand. It is the accompanied song stripped to its essentials. At times the right hand takes up the triplets too, in arpeggios rising to a note struck three times.
The left-hand triplets should flow with no bump on each downbeat, clearly softer than the melody they support. The delicate part is the ornamentation: the score has three trills and three grace notes, including a trill on G followed by two grace notes, F and G, leading into A. Count how many alternations you can play cleanly within the quarter note and stick to that number instead of shaking at random. The melody's half notes must really last: listen to them fade and place the next note inside that sound. The singing comes from those connections far more than from force.