Crew right to welcome mature person in charge (7)
I believe the answer is:
manager
'person in charge' is the definition.
(I've seen this before)
'crew right to welcome mature' is the wordplay.
'crew' becomes 'man' (I've seen this before).
'right' becomes 'r' (common abbreviation).
'to welcome' means one lot of letters goes inside another (in sense of 'inviting in').
'mature' becomes 'age' ('age' can be a synonym of 'mature').
'man'+'r'='manr'
'manr' enclosing 'age' is 'MANAGER'.
(Other definitions for manager that I've seen before include "Executive or controller" , "Sports team runner" , "Supervisor" , "executive position" , "head of department" .)