Flood defence completed following Depression (8)
I believe the answer is:
overflow
'flood' is the definition.
(I know that flood can be written as overflow)
'defence completed following depression' is the wordplay.
I cannot really see how this works, but
'completed' could be 'over' (synonyms) and 'over' is located in the answer.
'following' could be 'f' (used when citing page numbers etc) and 'f' is present in the answer.
'depression' could be 'low' (synonyms) and 'low' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for overflow that I've seen before include "Pipe to remove excess liquid" , "Spillage of excess liquid" , "Of water or crowd, spread beyond the usual limits" , "Flood" , "Drainage outlet" .)