Consequence of run in yard, rounding run out (9)
I believe the answer is:
corollary
'consequence' is the definition.
(thesaurus)
'run in yard rounding run out' is the wordplay.
'run in' becomes 'collar' (I am not sure about this - if you are sure you should believe this answer much more).
'yard' becomes 'y' (abbreviation).
'rounding' is an insertion indicator (some letters go round others).
'run out' becomes 'RO' (cricket abbreviation).
'collar'+'y'='collary'
'collary' placed around 'ro' is 'COROLLARY'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for corollary that I've seen before include "Proposition that follows logically" , "Direct consequence or result" , "Deduction; consequence" .)