Spluttered: 'Hot and cold running over!' (4)
I believe the answer is:
spat
'spluttered' is the definition.
(to splutter is to make spitting sounds)
'hot and cold running over' is the wordplay.
'hot and cold' becomes 'taps' (hot and cold taps).
'running over' says the letters should be written backwards (the letters turn over to the opposite direction).
'taps' in reverse letter order is 'SPAT'.
(Other definitions for spat that I've seen before include "Quarrel; oyster spawn" , "Minor conflict" , "Trivial quarrel" , "Legging covering instep and ankles" , "Taps in minor quarrel" .)