Do see I said I left the last to be readily trained (6)
I believe the answer is:
docile
'be readily trained' is the definition.
(I've seen this in another clue)
'do see i said i left the last' is the wordplay.
'see i said i left' becomes 'cil' (I can't justify this - if you can you should give a lot more credence to this answer).
'last' says to take the final letters.
The last letter of 'the' is 'e'.
'do'+'cil'+'e'='DOCILE'
'to' is the link.
Can you help me to learn more?
(Other definitions for docile that I've seen before include "Manageable" , "Coiled in submissive way" , "Easily managed and trainable" , "Meek and biddable" , "Tractable and pliant" .)