Standards followed by a helper as a rule (8)
I believe the answer is:
normally
'as a rule' is the definition.
(I've seen this in another clue)
'standards followed by a helper' is the wordplay.
'standards' becomes 'norm' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'followed by' means one lot of letters go next to another.
'a helper' becomes 'ally' (I've seen this in another clue).
'norm'+'ally'='NORMALLY'
Can you help me to learn more?
(Other definitions for normally that I've seen before include "By and large" , "Generally, usually" , "In the usual way" , "In the ordinary or typical way" , "In the usual manner" .)