Get naked with sweetheart for streak (6)
I believe the answer is:
stripe
'streak' is the definition.
(synonyms)
'get naked with sweetheart' is the wordplay.
'get naked' becomes 'strip' (strip off clothing).
'with' says to put letters next to each other.
'sweetheart' becomes 'e' (the middle letter or heart of 'sweet').
'strip'+'e'='STRIPE'
'for' is the link.
(Other definitions for stripe that I've seen before include "24 across (anag)" , "Braid showing military rank" , "Military mark of rank, chevron" , "Band of colour, maybe of rank" , "Distinctive band" .)