Her epic planner’s design and writer’s aid (6,9)
I believe the answer is:
pencil sharpener
'writer's aid' is the definition.
The definition suggests a singular noun which matches the answer.
'her epic planner's design' is the wordplay.
'design' indicates anagramming the letters.
'her'+'epic'+'planners'='herepicplanners'
'herepicplanners' anagrammed gives 'PENCIL-SHARPENER'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for pencil sharpener that I've seen before include "that makes lead go further" , "something struggling writer might resort to" , "shaving device" , "Desk item" , "It's used to make a point" .)