The old soldiers' current nationality (6)
I believe the answer is:
yemeni
'nationality' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'the old soldiers' current' is the wordplay.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'soldiers'' becomes 'men' (men can mean a group of soldiers).
'current' becomes 'I' (symbol for electric current).
'ye'+'men'+'i'='YEMENI'
Can you help me to learn more?
(Other definitions for yemeni that I've seen before include "Person from Sana'a, say" , "ME citizen" , "Coming from Aden?" , "Eg, native of Sana'a" , "Person from Aden perhaps" .)