Got there within a day, the river having flooded (7)
I believe the answer is:
arrived
'got there' is the definition.
(to arrive at a place is to get there)
'within a day the river having flooded' is the wordplay.
'within' means one lot of letters goes inside another.
'day' becomes 'd' (abbreviation for day).
'the river' becomes 'r' (abbreviation for river).
'having' means one lot of letters goes inside another.
'flooded' becomes 'rive' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'d'='ad'
'ad' enclosing 'r' is 'ard'.
'ard' going around 'rive' is 'ARRIVED'.
Can you help me to learn more?
(Other definitions for arrived that I've seen before include "A driver (anag.)" , "Reached a destination" , "Came" , "completed the journey" .)