One curate I trained who has lots to deal with (10)
I believe the answer is:
auctioneer
'who has lots to deal with' is the definition.
(a lot is an item for sale at auction)
'one curate i trained' is the wordplay.
'trained' indicates anagramming the letters (to train can mean to grow something into a shape).
'one'+'curate'+'i'='onecuratei'
'onecuratei' with letters rearranged gives 'AUCTIONEER'.
(Other definitions for auctioneer that I've seen before include "one that has lots to offer" , "One selling lots" , "One inviting bids for lots" .)