Oscar and I slink around in something waterproof (7)
I believe the answer is:
oilskin
'waterproof' is the definition.
(oilskin is a kind of waterproof)
'oscar and i slink around in' is the wordplay.
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'and' says to put letters next to each other.
'around' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'slink' anagrammed gives 'lskin'.
'i' inserted inside 'lskin' is 'ilskin'.
'o'+'ilskin'='OILSKIN'
'something' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for oilskin that I've seen before include "material" , "Heavy-duty waterproof" , "Waterproof cloth for rain-gear" , "security for a rainy day" , "Raincoat" .)