O look! See about saving ass! In Fagradalsfjall? (7)
I believe the answer is:
volcano
'o look see about saving' is the definition.
I can't judge whether this definition defines the answer.
'ass in fagradalsfjall?' is the wordplay.
'ass' becomes 'can' (synonyms).
'in' means one lot of letters goes inside another.
'fagradalsfjall?' becomes 'volo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'can' put inside 'volo' is 'VOLCANO'.
Can you help me to learn more?
(Other definitions for volcano that I've seen before include "Etna, for example" , "Scene of eruptions" , "Erupting mountain" , "Opening in earth's crust ejecting molten matter" , "St Helens?" .)