Mines the same, it's my steering box, adjusted it and it's no better but thing replacements are around £140 exchange but there are different types just make sure you get the right one.
As above though check everything else first as it could just be an easy fix
My 110 200tdi did this, was the earth on the inner wing, moved it to the bulkhead and now they work fine, before I did that I disconnected the washer pump wires and they worked, strange truck but it's all part of its charm
Mine does this, not all the time but really annoying.
It's my fuel lines making the ticking noise, stick your hear under the drivers rear wheel see if it's that, pulses the noise down the lines making it sound like its in the engine bay.
That's actually what it needs after it's rained, I do actually take some roundabouts quickly to empty foot wells on the way home from work, trouble is it runs in over the top of the door from the roof gutter and soaks me anyway haha
Just the throttle travel needed adjusting on mine, had slipped and wasn't getting full travel, fuel tank was changed too as after 20 years was full of all manor of ****e blocking the filter
I paid £2500 for my 200tdi but any defender for that money will need deep pockets.
I knew mine needed some welding etc but nothing on the scale I found when having a good dig around, 6 k plus later it has a new bulkhead and galvanised chassis, new brakes, suspension, fuel tank, full engine...
Mine used to do the same, shook when turning off and clattered.
I changed the engine mountings when I changed the chassis, made a small difference, turned out to be the fuel cut off solenoid, now I've replaced that it's fine.