Farm worker cultivated myriad, with help (9)
I believe the answer is:
dairymaid
'farm worker' is the definition.
(dairymaid is a kind of farm worker)
'cultivated myriad with help' is the wordplay.
'cultivated' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'help' becomes 'aid' (synonyms).
'myriad' with letters rearranged gives 'dairym'.
'dairym'+'aid'='DAIRYMAID'
(Other definitions for dairymaid that I've seen before include "Woman who milked cows" , "Person milking" , "Worker with milk, butter, etc" , "Midday air (anag.)" , "One used to parlour work" .)