Nanna has a rude sort of dignity (8)
I believe the answer is:
grandeur
'dignity' is the definition.
(I've seen this before)
'nanna has a rude sort' is the wordplay.
'nanna has' becomes 'gran' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sort' is an anagram indicator.
'rude' is an anagram of 'deur'.
'gran'+'deur'='GRANDEUR'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for grandeur that I've seen before include "Augustness" , "Magnificence - rare dung (anag)" , "Splendour, impressiveness" , "Loftiness" , "Majesty (God's, Hopkins)" .)