8 across
Unstructured
feature
of
shelf
reef
or
massif
(4-4)
Unstructured feature of shelf reef or massif (4-4)
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hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
Look at Unstructured — that's your definition. The rest of the clue hides the answer inside "shelf reef or massif", with "feature of" telling you it's lurking in there: shel-FREE-FORM-assif.