What a skindiver uses in South Island (5)
I believe the answer is:
scuba
'what a skindiver uses' is the definition.
I can't tell whether this definition defines the answer.
'south island' is the wordplay.
'south' becomes 'S' (synonyms).
'island' becomes 'cuba' (Cuba is an example).
's'+'cuba'='SCUBA'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for scuba that I've seen before include "breather" , "Diving equipment" , "Aqualung" , "Device that lets divers breathe under water" , "Self-contained underwater breathing apparatus (acronym)" .)