Four-wheeler put away, held by agent still? Not so (10)

'still? not so' is the definition.
(as in carbonated drinks as opposed to still)

'four-wheeler put away held by agent' is the wordplay.
'four wheeler' becomes 'car' (four-wheeled vehicle).
'put away' becomes 'ate' (put away can mean to eat).
'held by' indicates putting letters inside.
'agent' becomes 'bond' (James Bond).
'ate' going into 'bond' is 'bonated'.
'car'+'bonated'='CARBONATED'