Nurse briefly with certain valuables (8)
I believe the answer is:
treasure
'valuables' is the definition.
(I've seen this before)
'nurse briefly with certain' is the wordplay.
'nurse' becomes 'treat' (I've seen this before).
'briefly' means to remove the last letter.
'with certain' becomes 'sure' (synonyms. I am not sure about the 'with' bit.).
'treat' with its last letter taken off is 'trea'.
'trea'+'sure'='TREASURE'
(Other definitions for treasure that I've seen before include "Valuable hoard" , "... Island (R.L.Stevenson)" , "Highly prized possession" , "someone valued" , "... story by R.L. Stevenson" .)