Improve in quality (6)
'improve in quality' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for enrich that I've seen before include "Add to and improve" , "Grace" , "Aggrandize" , "Improve the quality by adding things" , "Adorn, enhance or make wealthy" .)
(Other definitions for enhance that I've seen before include "Intensify, increase or improve" , "Improve, make more attractive" , "Improve, add to attractiveness of" , "Heighten, intensify" , "Increase in power" .)