Reduce, restrict (7)
I believe the answer is:
curtail
I believe this is a double definition.
'reduce' is the first definition.
(I know that curtail is a more specific form of the action shorten)
'restrict' is the second definition.
(I know that restrict can be written as curtail)
(Other definitions for curtail that I've seen before include "Cut short (an activity)" , "'Cut short, restrict (7)'" , "Dock" , "Reduce in length" , "Reduce in extent" .)