One sent from master class (5)
I believe the answer is:
genus
'class' is the definition.
(I've seen this before)
'one sent from master' is the wordplay.
I cannot really see how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is found in the answer.
The remaining letters 'gnus' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for genus that I've seen before include "Part of the family" , "The Homo of Homo sapiens?" , "Category above species (Biology)" , "Taxonomic class between family and species" , "Taxonomic category above species" .)