Break in sandbar around large island (6)
I believe the answer is:
relief
'break' is the definition.
(I know that relief is a type of break)
'sandbar around large island' is the wordplay.
'sandbar' becomes 'reef' (I can't explain this - if you can you should give a lot more credence to this answer).
'around' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'island' becomes 'i'.
'l'+'i'='li'
'reef' going around 'li' is 'RELIEF'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for relief that I've seen before include "help for needy countries" , "Relatives" , "Rest - cure" , "A lightening of pressure" , "Easement from pain or stress" .)