Several who have taken the plunge (6)
I believe the answer is:
divers
'several' is the definition.
(I've seen this in another clue)
'taken the plunge' is the wordplay.
I cannot quite see how this works, but
'plunge' could be 'dive' (synonyms) and 'dive' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'who have' is the link.
Can you help me to learn more?
(Other definitions for divers that I've seen before include "Sundry - underwater explorers" , "Various; frogmen" , "people going to bed?" , "Some water-birds; assorted" , "competitors at the Olympic Games?" .)