Clumsy in record time (5)
I believe the answer is:
inept
'clumsy' is the definition.
('inept' can be a synonym of 'clumsy')
'in record time' is the wordplay.
'record' becomes 'ep'.
'time' becomes 't'.
'in'+'ep'+'t'='INEPT'
(Other definitions for inept that I've seen before include "Silly - unskilled - unsuitable" , "Clumsy and incompetent" , "Unsuitable, clumsy" , "Unskilful, awkward" , "Blundering" .)