Mum and Georgia brought in stray horse of renown (7)

'horse of renown' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'mum and georgia brought in stray' is the wordplay.
'mum' becomes 'sh' (both can mean to be quiet).
'and' means one lot of letters go next to another.
'georgia' becomes 'GA' (abbreviation for the US state).
'brought in' indicates putting letters inside.
'stray' becomes 'err' (to err is to stray or go wrong).
'ga' placed within 'err' is 'ergar'.
'sh'+'ergar'='SHERGAR'

Can you help me to learn more?