In breaking a rule, a doctor will not move fast (6)
I believe the answer is:
lumber
'not move fast' is the definition.
I can't judge whether this definition defines the answer.
'in breaking a rule a doctor' is the wordplay.
'in' indicates putting letters inside.
'breaking' is an anagram indicator.
'a doctor' becomes 'mb' (Bachelor of Medicine).
'rule' is an anagram of 'luer'.
'luer' placed around 'mb' is 'LUMBER'.
'will' is the link.
Can you help me to learn more?
(Other definitions for lumber that I've seen before include "With difficulty move" , "Move awkwardly; useless things" , "Wood for building - saddle" , "articles in storage" , "Burden with an unwanted task" .)