Yes more than 1000 a month (3)
I believe the answer is:
may
'month' is the definition.
(May is an example)
'yes more than 1000 a' is the wordplay.
'yes' becomes 'y'.
'more than' is a charade indicator (letters next to each other).
'm000' becomes 'm' (Roman numeral).
'm'+'a'='ma'
'y' put after 'ma' is 'MAY'.
(Other definitions for may that I've seen before include "plant that's tropical making comeback" , "UK PM" , "Hawthorm blossom" , "The merry merry month( 3)" , "Could" .)