Create sum of Attribute based on another attribute in same Entity

I thought this would be straight forward but I can’t work it out. I have this Entity  The LC Description is not fixed but essentially a list of categories. I simply want to create LC_ArableArea as the sum of LC_Area_ha where the LC_description is ‘Arable land’ Any ideas?
1 answers

Solved through a microflow using an iterator on a list with the context of the Master item.

Thanks for noticing my rookie mistake :0)