Restricts dog ends (8)
I believe the answer is:
curtails
'restricts' is the definition.
('curtail' can be a synonym of 'restrict')
'dog ends' is the wordplay.
'dog' becomes 'cur' (I've seen this before).
'ends' becomes 'tails' (tail is a kind of end).
'cur'+'tails'='CURTAILS'
(Other definitions for curtails that I've seen before include "Shortens" , "Cuts short, reduces" , "Places restrictions on" .)