Boss milks row with one of those cocooning, in the material sense (8)
I believe the answer is:
silkworm
'the material sense' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'boss milks row with one of those cocooning' is the wordplay.
'milks row' anagrams to 'SILKWORM'.
However, I'm not clear how this is indicated.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for silkworm that I've seen before include "It feeds on the 24" , "It feeds on mulberry leaves" , "Caterpillar yielding fine fibre" .)