Before repair, initially aim to stop very old machine giving out (6)
I believe the answer is:
vendor
'machine giving out' is the definition.
(a vending machine gives out items)
'before repair initially aim to stop very old' is the wordplay.
'before' is a charade indicator (letters next to each other).
'initially' says to take the initial letters.
'aim' becomes 'end' (I've seen this before).
'to stop' indicates putting letters inside.
'very old' becomes 'vo' (this might be a standard abbreviation which I don't know about).
The first letter of 'repair' is 'r'.
'end' placed into 'vo' is 'vendo'.
'r' after 'vendo' is 'VENDOR'.
(Other definitions for vendor that I've seen before include "Person selling" , "Salesperson" , "Seller, trader (O, not E)" , "Purveyor" , "A Latin seller" .)