Clumsy in disturbing a pet (5)
I believe the answer is:
inept
'clumsy' is the definition.
(I know that clumsy can be written as inept)
'in disturbing a pet' is the wordplay.
'disturbing' indicates anagramming the letters (I've seen this in other clues).
'pet' anagrammed gives 'ept'.
'in'+'ept'='INEPT'
(Other definitions for inept that I've seen before include "Showing a lack of competence" , "Wanting" , "Maladroit" , "pointless" , "Foolish" .)