Guided through central Leon, missile finds old capital (6)
I believe the answer is:
escudo
'capital' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'guided through central leon missile finds old' is the wordplay.
'guided through central leon' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'missile' becomes 'scud' (type of long-range missile).
'finds' means one lot of letters go next to another.
'old' becomes 'o' (abbreviation).
'e'+'scud'+'o'='ESCUDO'
Can you help me to learn more?
(Other definitions for escudo that I've seen before include "Former Portuguese monetary unit" , "US code, oddly, used in Portugal until recently" , "Old monetary unit of Portugal" , "Smash in C Verde" , "Former unit of money in Portugal" .)