Here’s the preamble in full:
Clues are presented in the correct order. The completed grid, which does not have one letter per square, displays mirror symmetry, and resembles the item given by the unclued entry (verifiable, though not the precise form used, in the Oxford Dictionary of English). Clue numbers and bars must not be entered. Those letters which are not one per square, when combined with those in the four shaded cells, can be rearranged to give a thematic word which must be written under the grid. Chambers Dictionary (2014) is recommended, but does not contain one reasonably common foreign word; one entry is an abbreviation.