Chap mostly in charge of enhancing stock (7)
I believe the answer is:
eugenic
'enhancing stock' is the definition.
I can't judge whether this defines the answer.
'chap mostly in charge' is the wordplay.
'chap mostly' becomes 'eugen' (I am not sure about the 'mostly' bit.).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'eugen'+'ic'='EUGENIC'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for eugenic that I've seen before include "Using controlled breeding to mould population" , "To do with science of controlled animal breeding" , "breeding better stock" , "Concerned with racial improvement" , "For improving stock" .)