Month before it turns up south of an island (7)
I believe the answer is:
antigua
'island' is the definition.
(I know that Antigua is a island)
'month before it turns up south of an' is the wordplay.
'month' becomes 'aug' (abbreviation for August).
'before' is a charade indicator (letters next to each other).
'turns up' shows that the letters should be reversed in order.
'south of' says to put letters next to each other (in a down clue, some letters go under others).
'aug'+'it'='augit'
'augit' back-to-front is 'tigua'.
'tigua' put after 'an' is 'ANTIGUA'.
(Other definitions for antigua that I've seen before include "One of the Leeward Islands" , "warm island" , "West Indies island" , "holiday destination" , "Largest of Leeward Is." .)