Beast about ninety in American wagon (6)
I believe the answer is:
boxcar
'american wagon' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'beast about ninety' is the wordplay.
'beast' becomes 'boar' (I can't explain this - if you can you should believe this answer much more).
'about' is an insertion indicator.
'ninety' becomes 'XC' (Roman numerals).
'boar' going around 'xc' is 'BOXCAR'.
'in' is the link.
Can you help me to learn more?
(Other definitions for boxcar that I've seen before include "US railway wagon" , "Freight wagon (US)" .)