Unfit yet it goes around the pen (5)
I believe the answer is:
inept
'unfit' is the definition.
(thesaurus)
'it goes around the pen' is the wordplay.
'goes around' means one lot of letters goes inside another.
'the pen' becomes 'nep' (I am not sure about this - if you are sure you should believe this answer much more).
'it' enclosing 'nep' is 'INEPT'.
'yet' acts as a link.
Can you help me to learn more?
(Other definitions for inept that I've seen before include "Ham-fisted" , "Hopelessly incapable" , "Clumsy, out of place" , "Clumsy, bumbling" , "Cack-handed" .)