A harbour was breached and flooded (5)
I believe the answer is:
awash
'flooded' is the definition.
(synonyms)
'a harbour was breached' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
The remaining letters 'wash' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for awash that I've seen before include "not quite under" , "Overflowing" , "Flood" , "Flooded; about to sink" , "becomes flooded" .)