Aggressive former royal, one with beef (7)
I believe the answer is:
butcher
'beef' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'aggressive former royal one' is the wordplay.
I cannot really see how this works, but
'royal' could be 'er' (abbreviation for Elizabeth Regina) and 'er' is found in the answer.
The remaining letters 'butch' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'with' is the link.
Can you help me to learn more?
(Other definitions for butcher that I've seen before include "mess up?" , "Killer" , "He cuts up and sells meat" , "One sells meat" , "Kill brutally" .)