Laboratory rat in a school, on reflection, should keep clean (8)
I believe the answer is:
sanitary
'clean' is the definition.
(I've seen this before)
'laboratory rat in a school on reflection' is the wordplay.
'laboratory' becomes 'yin' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'school' becomes 'S'.
'on reflection' shows that the letters should be reversed in order.
'yin' going around 'rat' is 'yratin'.
'yratin'+'a'+'s'='yratinas'
'yratinas' reversed gives 'SANITARY'.
'should keep' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sanitary that I've seen before include "Free from filth and pathogens" , "Free from dirt or infective matter" , "Astray in hygienic way" , "Relating to hygiene" , "Relating to health" .)