Protective envelope used by businesses getting ahead (6)
I believe the answer is:
cocoon
'protective envelope' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'businesses getting ahead' is the wordplay.
'businesses' becomes 'coco' (I can't explain this - if you can you should believe this answer much more).
'getting' says to put letters next to each other.
'ahead' becomes 'on' (synonyms).
'coco'+'on'='COCOON'
'used by' acts as a link.
Can you help me to learn more?
(Other definitions for cocoon that I've seen before include "Envelop for protection" , "Wrap; pupa's protection" , "Protect" , "Larva case" , "Protective case for insect" .)