She favours young people who manage livestock holding back of Bourke (6)
I believe the answer is:
ageist
'she favours young people who manage livestock holding back of bourke' is the definition.
The definition suggests a singular noun which matches the answer.
'she' is the wordplay.
I cannot quite understand how this works, but
'she' could be 'ag' and 'ag' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ageist that I've seen before include "being for youngsters only?" , "One who discriminates against on grounds of age" , "against vets" , "discriminator of old" , "making it hard for the elderly" .)