Mollusc providing world of opportunities? (6)
I believe the answer is:
oyster
'mollusc' is the definition.
(I know that oyster is a type of bivalve)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for oyster that I've seen before include "Pearl-making mollusc" , "aphrodisiac?" , "World as place of opportunity" , "pale pink" , "Storey (anag)" .)