One stratagem about PR that's better (7)
I believe the answer is:
improve
'better' is the definition.
(synonyms)
'one stratagem about pr' is the wordplay.
'one stratagem' becomes 'imove' (I can't justify this - if you can you should believe this answer much more).
'about' is an insertion indicator.
'imove' going around 'pr' is 'IMPROVE'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for improve that I've seen before include "Make better in quality" , "Make progress" , "Train" , "Enhance" , "reform" .)