Not totally unrestricted speed in run (7)
I believe the answer is:
operate
'run' is the definition.
(I know that run can be written as operate)
'not totally unrestricted speed' is the wordplay.
'not totally' means to remove the last letter.
'unrestricted' becomes 'open' (similar in meaning).
'speed' becomes 'rate' (the speed at which something happens).
'open' with its final letter taken away is 'ope'.
'ope'+'rate'='OPERATE'
'in' is the link.
(Other definitions for operate that I've seen before include "Work - perform surgery" , "Manage, run" , "Carry on business" , "(Of machine) function" , "Perform surgery or run a machine" .)