Cut short dog-end (7)
I believe the answer is:
curtail
'cut short' is the definition.
(synonyms)
'dog-end' is the wordplay.
'dog' becomes 'cur' (both can mean a despicable person).
'end' becomes 'tail' (tail is a kind of end).
'cur'+'tail'='CURTAIL'
(Other definitions for curtail that I've seen before include "make shorter" , "Abbreviate" , "Impose a restriction on" , "Shorten, abridge" , "Cut short (an activity)" .)