Spilling a pint - clumsy (5)
I believe the answer is:
inapt
'clumsy' is the definition.
(I know that clumsy can be written as inapt)
'spilling a pint' is the wordplay.
'spilling' is an anagram indicator.
'a'+'pint'='apint'
'apint' is an anagram of 'INAPT'.
(Other definitions for inapt that I've seen before include "Unsuitable - paint (anag)" , "badly judged" , "Unsuited" , "Improper" , "Not fit, unsuitable" .)