A dog to hire for the present (7)
I believe the answer is:
current
'the present' is the definition.
(I've seen this before)
'a dog to hire' is the wordplay.
'a dog' becomes 'cur' (both can mean a despicable person).
'to hire' becomes 'rent' ('rent' can be a synonym of 'hire').
'cur'+'rent'='CURRENT'
'for' is the link.
(Other definitions for current that I've seen before include "Up-to-date" , "In general use; flow" , "unlike these pieces" , "Present - tide" , "flower" .)