Many letters could be the reason the postie wears gloves? (8)
I believe the answer is:
mailshot
'many letters' is the definition.
'mailshot' can be an answer for 'letters' (I've seen this before). I am not sure about the 'many' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mailshot that I've seen before include "Mass dispatch of letters" , "Leaflet sent to a large group at the same time" , "Postal item, often junk" , "Promotional items widely dispatched" , "commercial literature" .)