Man requiring you to separate colt from young cow (3)
I believe the answer is:
alf
'man' is the definition.
(short for Alfred)
'colt from young cow' is the wordplay.
'colt' becomes 'c' (horseracing abbreviation).
'from' indicates named letters should be taken away.
'young cow' becomes 'calf' (a calf is a young cow).
'calf' with 'c' taken out is 'ALF'.
'requiring you to separate' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for alf that I've seen before include "See man" , "Boy" , "Sir - Ramsey, England footballer and manager" , "-- Garnett, bigoted TV?character" , "Mr Garnett" .)