Otherwise cool van could erupt (7)
I believe the answer is:
volcano
'could erupt' is the definition.
I can't judge whether this defines the answer.
'otherwise cool van' is the wordplay.
'otherwise' is an anagram indicator.
'cool'+'van'='coolvan'
'coolvan' is an anagram of 'VOLCANO'.
Can you help me to learn more?
(Other definitions for volcano that I've seen before include "Scene of eruptions" , "Erupting hole in the earth's crust" , "Vent in earth's crust" , "eg Mount Etna" , "One expelling lava etc." .)