Marked with streaks or blotches (7)
I believe the answer is:
mottled
'marked with streaks or blotches' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mottled that I've seen before include "Blotched" , "Marked with spots" , "Having blotches of colour" , "Blotchy" , "Marked with streaks or blotches" .)