A blood disorder gets one a game (7)
I believe the answer is:
diabolo
'game' is the definition.
(I've seen this before)
'a blood disorder gets one a' is the wordplay.
'disorder' indicates anagramming the letters (a disordered version of the letters).
'gets' is an insertion indicator (gets can mean captures or absorbs).
'one' becomes 'i' (Roman numeral).
'blood' with letters rearranged gives 'dbolo'.
'i'+'a'='ia'
'dbolo' enclosing 'ia' is 'DIABOLO'.
(Other definitions for diabolo that I've seen before include "Game involving two sticks joined by a string and a spool-shaped object" , "Game involving sticks and spinning top" , "Game of catching spinning-top" , "Devilish" , "children's game?" .)