Book has the ability to offend for a start -- might one blow one's top? (7)
I believe the answer is:
Here is my best explanation:
'a start might one blow one's top?' is the definition.
I can't judge whether this defines the answer.
'book has the ability to offend' is the wordplay.
'book' becomes 'vol'.
'has the ability to' becomes 'can' (I've seen this before).
'offend' becomes 'o' (this could be a standard abbreviation which I don't know about).
'for' acts as a link.
(Other definitions for volcano that I've seen before include "kind of mountain", "Fiery mountain", "Exploding mountain", "Scene of eruptions", "Site of eruption", "Erupting mountain", "Type of mountain", "Eg, Eyjafjallajokull", "E.g. Vesuvius, Etna" and "Vent in earth's crust".)