Seafood requisitions taking months, not days (6)

I believe the answer is:

ormers

'seafood' is the definition.
(ormer is a type of edible mollusc)

I don't understand how the rest of the clue works.

(Another definition for ormers that I've seen is " Shells".)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app