Traditional military leader initially takes in young girl (7)
I believe the answer is:
classic
'traditional' is the definition.
(I've seen this before)
'in young girl' is the wordplay.
'in' indicates putting letters inside.
'young' becomes 'cic' (I can't justify this - if you can you should give a lot more credence to this answer).
'girl' becomes 'lass' (lass can informally mean a girl).
'cic' enclosing 'lass' is 'CLASSIC'.
'military leader initially takes' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for classic that I've seen before include "Timeless-quality work; a race" , "Creation of the highest standard" , "work of the highest quality" , "Derby, say" , "Important horse race" .)