
1) British enlisted soldiers 2) Ones doing an ordering job 3) Promoted officers
Found on
https://www.crosswordclues.com/clue/rankers

Rankers are soils developed over non-calcareous material, usually rock. They are regarded in some soil classifications as lithomorphic soils, a group which also includes rendzinas, similar soils over calcareous material. They are often called A/C soils, as the topsoil or A horizon is immediately over a C horizon (unaltered parent material). ...
Found on
http://en.wikipedia.org/wiki/Rankers
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