Oscar, member of Upper House, welcomes new cricketer (6)
I believe the answer is:
opener
'cricketer' is the definition.
(batsman who opens the batting)
'oscar member of upper house welcomes new' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'member of upper house' becomes 'peer' (member of the House of Lords).
'welcomes' means one lot of letters goes inside another (in sense of 'invites in').
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'peer' enclosing 'n' is 'pener'.
'o'+'pener'='OPENER'
(Other definitions for opener that I've seen before include "Leading cricketer" , "First in batting order" , "First part" , "In cricket, a batsman who plays the first ball of an innings" , "It may provide access to food" .)