Being clumsy, it holds a pen awkwardly (5)
I believe the answer is:
inept
'being clumsy' is the definition.
('inept' can be a synonym of 'clumsy')
'it holds a pen awkwardly' is the wordplay.
'holds' means one lot of letters goes inside another.
'awkwardly' is an anagram indicator.
'pen' with letters rearranged gives 'nep'.
'it' going around 'nep' is 'INEPT'.
(Other definitions for inept that I've seen before include "Amateurish" , "Hopeless; bungling" , "Unskilful, awkward" , "Awkward, clumsy" , "Ham-fisted" .)