Appeal to embrace Norse god of overabundance (8)
I believe the answer is:
plethora
'overabundance' is the definition.
(I've seen this in another clue)
'appeal to embrace norse god of' is the wordplay.
'appeal' becomes 'plea' (plea is a kind of appeal).
'to embrace' means one lot of letters goes inside another.
'norse god of' becomes 'thor' (I can't explain this - if you can you should believe this answer much more).
'plea' going around 'thor' is 'PLETHORA'.
Can you help me to learn more?
(Other definitions for plethora that I've seen before include "Large number" , "opposite of scarcity" , "Embarrassment" , "Excessively large amount" , "'Large, perhaps excessive, amount (8)'" .)