Woman wearing a kid’s first waterproof jacket (6)
I believe the answer is:
anorak
'waterproof jacket' is the definition.
(I've seen this before)
'woman wearing a kid's first' is the wordplay.
'woman' becomes 'nora' (**).
'wearing' is an insertion indicator.
'first' suggests taking the first letters.
The first letter of 'kids' is 'k'.
'a'+'k'='ak'
'nora' going within 'ak' is 'ANORAK'.
(Other definitions for anorak that I've seen before include "Zipped jacket with hood attached" , "Jacket for an obsessive?" , "Nerdy type" , "Mikado's son (G&S)" , "Hooded waterproof jacket" .)