Self-confident young woman removing top on river north of Germany (7)
I believe the answer is:
assured
'self-confident' is the definition.
(I've seen this in another clue)
'young woman removing top on river north of germany' is the wordplay.
'young woman' becomes 'lass' (informal term for a young woman).
'removing top' means to remove the first letter (I've seen 'removes top' mean this).
'on river' becomes 'ure' (I can't explain this - if you can you should believe this answer much more).
'north of' says to put letters next to each other (in a down clue, some letters go above others).
'germany' becomes 'd' (vehicle registration code for Deutschland).
'lass' with its first letter taken off is 'ass'.
'ass'+'ure'+'d'='ASSURED'
Can you help me to learn more?
(Other definitions for assured that I've seen before include "Gave confidence to" , "Self-confident" , "Informed with certainty and confidence" , "Sad ruse (anag.)" , "Confident, secure" .)