Odd spiel might be unbalanced (8)
I believe the answer is:
lopsided
'unbalanced' is the definition.
(I've seen this before)
'odd spiel might be' is the wordplay.
'might be' indicates an anagram.
'odd'+'spiel'='oddspiel'
'oddspiel' is an anagram of 'LOPSIDED'.
(Other definitions for lopsided that I've seen before include "not evenly distributed" , "Ill-balanced" , "Askew, wonky" , "Off balance" , "Askew, awry" .)