Quick to learn a key part (5)
I believe the answer is:
ready
'quick' is the definition.
(similar in meaning)
'learn a key part' is the wordplay.
'learn' becomes 'read' (synonyms).
'a key part' becomes 'y' (I can't justify this - if you can you should give a lot more credence to this answer).
'read'+'y'='READY'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for ready that I've seen before include "Quick" , "All set to go" , "Cash; within reach" , "rough companion" , "game?" .)