Being active in taking the dog out (5)
I believe the answer is:
doing
'being active' is the definition.
(I've seen this in another clue)
'in taking the dog out' is the wordplay.
'taking' says to put letters next to each other.
'out' indicates an anagram (out can mean wrong or inaccurate).
'in'+'dog'='indog'
'indog' with letters rearranged gives 'DOING'.
(Other definitions for doing that I've seen before include "Carrying out action" , "Accomplishing" , "Effecting" , "Faring" , "Engaged in -- active" .)