Tells one the way to train the rose round it (6)
I believe the answer is:
orders
'tells' is the definition.
('order' can be a synonym of 'tell')
'train the rose round it' is the wordplay.
'train' indicates an anagram (to train can mean to grow something into a shape).
'round' indicates putting letters inside.
'it' becomes 'rd' (I can't justify this - if you can you should give a lot more credence to this answer).
'rose' is an anagram of 'oers'.
'oers' placed around 'rd' is 'ORDERS'.
'one the way to' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for orders that I've seen before include "Holy - -" , "Instructions given as to waiters" , "Dictates, commands" , "Commands and edicts" , "Commands these priests and nuns?" .)