Dance music has old German prince shaking his tail (7)
I believe the answer is:
electro
'dance music' is the definition.
(I've seen this before)
'old german prince shaking his tail' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'german prince' becomes 'elector' (I've seen this before).
'shaking' is a deletion indicator (to shake can mean to lose or get rid of).
'his tail' becomes 'o' (I am not sure about this - if you are sure you should believe this answer much more).
'elector' with 'o' taken away is 'electr'.
'electr'+'o'='ELECTRO'
'has' acts as a link.
Can you help me to learn more?
(Other definitions for electro that I've seen before include "Modern music" , "printing plate" , "Style of dance music" , "Printing-plate (abbrev.)" .)