An ounce of white stuff - and fixed parole date! (4,7)
I believe the answer is:
snow leopard
'an ounce' is the definition.
('snow leopard' can be a synonym of 'ounce')
'white stuff and fixed parole date' is the wordplay.
'white stuff' becomes 'snow' (I've seen this before).
'and' says to put letters next to each other.
'fixed' indicates anagramming the letters.
'date' becomes 'd' (common abbreviation eg in DOB, date of birth).
'parole' with letters rearranged gives 'leopar'.
'snow'+'leopar'+'d'='SNOW-LEOPARD'
'of' acts as a link.
(Other definitions for snow leopard that I've seen before include "Ounce (carnivore)" , "Rare mountain cat" , "Rare large cat" .)