Graphics text clearing

I am using DisplayPack2 with a standard Pi pico board and the C SDK . I have extended the Pimoroni graphics package to use the Arduino FreeFont fonts and it all works fine except that writing a line of text over another line of text does not clear the initial text line.
I could call clear() but this will clear the entire screen. What is the standard method for clearing a line of text before the next call to text() to draw the new text line ?

I can’t comment on how it goes in C. But I’m using a Display Pack in Micro Python.
I do all my display text etc to the buffer, then an update display, display clear. wash rinse and repeat.
I’m more often than not changing multiple characters, in different locations, on the screen.
Best guess is the new text only changes the pixels it uses when its written to the display buffer. Drawing a black box over the old text, then writing the new text to the buffer “should” work? It’s how i would do it in Python. Apologies if that ends up being a PITA in C.