Coming up, top island chap, hard-working (8)
I believe the answer is:
diligent
'hard-working' is the definition.
(I've seen this before)
'coming up top island chap' is the wordplay.
'coming up top island' becomes 'dili' (I am not sure about this - if you are sure you should believe this answer much more).
'chap' becomes 'gent' (both can mean a man).
'dili'+'gent'='DILIGENT'
Can you help me to learn more?
(Other definitions for diligent that I've seen before include "Taking trouble" , "Attentive and busy" , "Assiduous" , "Industrious" , "Painstaking - I tingled (anag)" .)