First of casualties in war, score shocking — frightening figure? (9)
I believe the answer is:
scarecrow
'frightening figure?' is the definition.
'first of casualties in war score shocking' is the wordplay.
'first of casualties' becomes 'c' (1st letter of 'casualties').
'in' means one lot of letters goes inside another.
'shocking' is an anagram indicator (letters shocked or shaken).
'war'+'score'='warscore'
'warscore' with letters rearranged gives 'sarecrow'.
'c' inserted inside 'sarecrow' is 'SCARECROW'.
(Other definitions for scarecrow that I've seen before include "pest controller" , "one deters" , "What drives away" , "Badly-dressed person" , "he's shabbily dressed" .)