The X-man's right to catch a rodent (7)
I believe the answer is:
muskrat
'rodent' is the definition.
(muskrat is a kind of rodent)
'the x-man's right to catch a' is the wordplay.
'the x man's' becomes 'musk' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'right' becomes 'rt' (abbreviation as in Rt Hon- the Right Honourable).
'to catch' means one lot of letters goes inside another.
'rt' placed around 'a' is 'rat'.
'musk'+'rat'='MUSKRAT'
Can you help me to learn more?
(Other definitions for muskrat that I've seen before include "Large aquatic rodent" , "Beaver-like rodent with glossy brown fur" , "Rodent valued for its fur" , "Large, smelly North American rodent" , "UK, smart? (anag)" .)