Hot and sunny periodically, leading to fruit deluge (8)
I believe the answer is:
inundate
'deluge' is the definition.
(I know that deluge can be written as inundate)
'hot and sunny periodically leading to fruit' is the wordplay.
'hot' becomes 'in' (both can mean fashionable).
'and' means one lot of letters go next to another.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
'leading to' is a charade indicator (letters next to each other) (some letters go before or lead others).
'fruit' becomes 'date' (date is a kind of fruit).
The alternate letters of 'sunny' are 'un'.
'in'+'un'+'date'='INUNDATE'
(Other definitions for inundate that I've seen before include "Aunt Enid could engulf badly" , "be overwhelming" , "Flood, cover with water" , "Overwhelm (as if) with water" , "Flood (a place)" .)