The principal's inflection of voice is a tribute to the dead (9)
I believe the answer is:
headstone
'voice is a tribute to the dead' is the definition.
I can't tell whether this defines the answer.
'the principal's inflection' is the wordplay.
'the principal's' becomes 'heads' ('head' can be a synonym of 'principal').
'inflection' becomes 'tone' (I've seen this in another clue).
'heads'+'tone'='HEADSTONE'
'of' is the link.
Can you help me to learn more?
(Other definitions for headstone that I've seen before include "It is set up on a grave with inscriptions" , "It marks a grave" , "Grave marker" , "Its stands over a grave, duly inscribed" , "Slab set at the head of a grave" .)