Words of praise not rare (4,4)
I believe the answer is:
well done
'words' is the definition.
(I have seen 'Words of praise' mean 'well done' so perhaps 'words' could also mean 'well done')
'praise not rare' is the wordplay.
'praise' becomes 'well' (I am not sure about this - if you are sure you should believe this answer much more).
'not rare' becomes 'done' (I've seen this in another clue).
'well'+'done'='WELL-DONE'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for well done that I've seen before include "Congratulations - cooked right through" , "How one might like one's steak?" , "expression of approval" , "Congratulations - certainly not rare!" , "Far from rare" .)