Nasty stain here he removed – something fatty (7)
I believe the answer is:
stearin
'nasty stain here he removed something fatty' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'nasty stain here he removed' is the wordplay.
'nasty' indicates anagramming the letters (a nasty or wrong spelling).
'removed' indicates named letters should be taken away.
'stain'+'here'='stainhere'
'stainhere' with 'he' taken away is 'stainre'.
'stainre' with letters rearranged gives 'STEARIN'.
Can you help me to learn more?
(Other definitions for stearin that I've seen before include "A constituent of tallow" , "Fatty stuff" , "Fatty chemical" , "mixture of fatty acids" , "Part of fat" .)