Cast may need this, seeing a part rewritten (11*)
'cast may need this' is the definition.
The definition suggests a singular noun which matches the answer.
'seeing a part rewritten' is the wordplay.
'rewritten' indicates anagramming the letters.
'seeingapart' is an anagram of 'GREASE PAINT'.
Can you help me to learn more?
(Other definitions for grease paint that I've seen before include "Theatrical make-up", "Actor's make-up".)