Underwater swimmer drives excitedly across Caribbean island (5,5)
I believe the answer is:
scuba diver
'underwater swimmer' is the definition.
(I've seen this before)
'drives excitedly across caribbean island' is the wordplay.
'excitedly' is an anagram indicator.
'across' means one lot of letters goes inside another.
'caribbean island' becomes 'cuba' (I've seen this before).
'drives' is an anagram of 'sdiver'.
'sdiver' going around 'cuba' is 'SCUBA DIVER'.
(Other definitions for scuba diver that I've seen before include "Underwater swimmer" , "Let in air" .)