Wife in nude, rear designed for knickers, say! (9)
I believe the answer is:
underwear
'knickers say' is the definition.
(I know that bloomers is a type of underpants)
'wife in nude rear designed' is the wordplay.
'wife' becomes 'w' (abbreviation).
'in' means one lot of letters goes inside another.
'designed' indicates an anagram (designed with the letters).
'nude'+'rear'='nuderear'
'nuderear' anagrammed gives 'underear'.
'w' placed into 'underear' is 'UNDERWEAR'.
'for' is the link.
(Other definitions for underwear that I've seen before include "Vest, pants etc" , "Garments worn beneath other clothes" , "shift, perhaps" , "Lingerie" , "Endure war about smalls" .)