A cold wet nursery deters boy playing (6,3)
I believe the answer is:
oyster bed
'a cold wet nursery' is the definition.
(area built to breed oysters)
'deters boy playing' is the wordplay.
'playing' indicates anagramming the letters.
'deters'+'boy'='detersboy'
'detersboy' is an anagram of 'OYSTER-BED'.
(Other definitions for oyster bed that I've seen before include "seafood supplier" , "stew, perhaps" , "Source of pearls" , "breeding ground" , "A source of seafood" .)