Crossword clue: the folding in of an outer layer so as to form a pocket in the surface
2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
the folding in of an outer layer so as to form a pocket in the surface
the folding in of an outer layer so as to form a pocket in the surface