Cardinal’s assistant, initially receiving a rise (9)
I believe the answer is:
paramount
'cardinal's' is the definition.
(thesaurus)
'assistant initially receiving a rise' is the wordplay.
'assistant' becomes 'PA' (personal assistant).
'initially' indicates taking the first letters.
'rise' becomes 'mount' (both can mean to increase).
The first letter of 'receiving' is 'r'.
'pa'+'r'+'a'+'mount'='PARAMOUNT'
(Other definitions for paramount that I've seen before include "First" , "More important than anything else" , "Of overriding importance" , "Supreme - Hollywood studio" , "Pre-eminent - movie maker" .)