There was no marker for the quest [Clamlette Surprise] but the quest was available.
Note that this is not old Vanilla quest of the same name (id=6610), it is WotLK 'upgrade' variant (id=13825).

https://www.wowhead.com/wotlk/quest=13825/clamlette-surprise

v7.0.1
WotLK pre-patch

Fixed in c2712b2