A drive in rain for lover (8)
I believe the answer is:
paramour
'lover' is the definition.
(paramour is a kind of lover)
'a drive in rain' is the wordplay.
'drive' becomes 'ram' (RAM drive on a computer).
'in' is an insertion indicator.
'rain' becomes 'pour' (pouring is a kind of raining).
'a'+'ram'='aram'
'aram' inserted inside 'pour' is 'PARAMOUR'.
'for' acts as a link.
(Other definitions for paramour that I've seen before include "A lover, illicit perhaps" , "courtesan" , "fancy woman" , "Lover, especially of a married person" , "wife's toy boy, for example" .)