After short run do oppose the surge (5)
I believe the answer is:
flood
'the surge' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for flood that I've seen before include "Inundate" , "Overflow of water" , "Oversupply" , "Light" , "Inundation" .)