Get a rule prepared to adjust (8)
I believe the answer is:
regulate
'adjust' is the definition.
(regulating is a kind of adjusting)
'get a rule prepared' is the wordplay.
'prepared' indicates an anagram.
'get'+'a'+'rule'='getarule'
'getarule' with letters rearranged gives 'REGULATE'.
'to' is the link.
(Other definitions for regulate that I've seen before include "Ate gruel (anag.)" , "Bring order" , "Control or direct by means of rules and procedures" , "Control, supervise" , "Control, manage" .)