Spilled a pint being clumsy (5)
I believe the answer is:
inapt
'being clumsy' is the definition.
(synonyms)
'spilled a pint' is the wordplay.
'spilled' indicates an anagram.
'a'+'pint'='apint'
'apint' is an anagram of 'INAPT'.
(Other definitions for inapt that I've seen before include "Not proper" , "Not suitable or appropriate" , "Free from deceit" , "Ill-chosen, not suitable" , "Cartoon duck" .)