Waterproof being worn is red (5)
I believe the answer is:
macon
'is red' is the definition.
(type of red wine)
'waterproof being worn' is the wordplay.
'waterproof' becomes 'mac' (mac is a kind of waterproof).
'being worn' becomes 'on'.
'mac'+'on'='MACON'
(Other definitions for macon that I've seen before include "red" , "Burgundian wine" , "Variety of Burgundy" , "Wandering (knight)" , "French wine district" .)