There are words that end with z and begin with most letters. However, there are no words in the English language that begin with y and end with z.
cat
zany
There is no word in the English language that starts with Y and ends with Z.
alchochaz
Zebra
A five (5) letter word that starts with Z and ends with F, there is none recorded. However, there is a word that starts with Z and ends with F. The word is a four (4) letter word: zarf, (noun) a metal holder for a coffee cup.
wiz?
Zanex
ditz
The "alphabet".
zoa
zeefe