Apprehension about the quill (7)
I believe the answer is:
feather
'quill' is the definition.
(thesaurus)
'apprehension about the' is the wordplay.
'apprehension' becomes 'fear' (I've seen this before).
'about' indicates putting letters inside.
'fear' enclosing 'the' is 'FEATHER'.
(Other definitions for feather that I've seen before include "One of a bird's waterproof covering" , "dance step" , "In your cap, this represents an achievement" , "trifling thing" , "Part of covering of bird" .)