Farm hand is constant female with lowered head (6)
I believe the answer is:
Here is my best explanation:
This could be a double definition.
'farm hand' is the first definition.
'constant female with lowered head' is the second definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'is' is the link.
(Other definitions for cowman that I've seen before include "tender", "Tender of cattle" and "Stocky chap".)