Flood defence god using hammer breaches (8)
I believe the answer is:
plethora
'flood' is the definition.
(I've seen this before)
'defence god using hammer breaches' is the wordplay.
I cannot really understand how this works, but
'god' could be 'thor' (Thor is an example) and 'thor' is found within the answer.
'defence' could be 'plea' (plea is a kind of defence) and 'plea' is found in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for plethora that I've seen before include "Excessive quantity" , "Abundant supply" , "Unnecessarily large quantity" , "More than enough" , "Superabundance" .)