The sun is setting, or rising, in the top right-hand corner of that image.
It is clearly a bit of a dusty or hazy day.
The best way of dealing with a scenario like this is in-camera.
Try a polarising filter - these work best when orientated at 90 degrees to the direction of the sunlight.
Clearly, shooting via a drone means a lot of thought and planning prior to shooting is necessary to use a polariser effectively with a camera attached to a drone...
Also, depending on the cause of that haze,, shooting at a different time of day may help. I get the impression that this was a late afternoon shot. There is often more atmospheric haze late in the day than compared to early morning - unless the cause is a temperature inversion which is always worse around sunrise. Either way, if you want to become a successful outdoor photographer it is essential that you learn to understand the physics of light as well as the weather and atmospheric conditions that affect the light...
Cletus is entirely correct when he suggests shooting in raw - it makes any post-processing required MUCH easier to accomplish - however, issues such as yours are much more effectively dealt with in-camera!
Tony Jay