Leading lady welcoming a Liberal peer (4)
I believe the answer is:
earl
'peer' is the definition.
(I know that earl is a type of peer)
'leading lady welcoming a liberal' is the wordplay.
'leading lady' becomes 'ER' (Elizabeth Regina).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'liberal' becomes 'l' (abbreviation).
'er' enclosing 'a' is 'ear'.
'ear'+'l'='EARL'
(Other definitions for earl that I've seen before include "A real titled lord" , "Aristocrat ranking between marquis and viscount" , "Countesss husband" , "A lord like Lear" , "Male member of British nobility" .)