Last letter home has finally tragic element (4)
I believe the answer is:
zinc
'element' is the definition.
(zinc is a kind of element)
'last letter home has finally tragic' is the wordplay.
'last letter' becomes 'z' (last letter of the alphabet).
'home' becomes 'in' ('he's home' can mean 'he's in').
'has' says to put letters next to each other.
'finally' indicates one should take the final letters.
The last letter of 'tragic' is 'c'.
'z'+'in'+'c'='ZINC'
(Other definitions for zinc that I've seen before include "Constituent of brass" , "Bluish-white lustrous metallic element" , "Penultimate element (alpha. order)" , "Sivery-white metal" , "Metal used in galvanising iron" .)