Better money needed to secure a master (7)
I believe the answer is:
captain
'master' is the definition.
(both can mean a leader)
'better money needed to secure a' is the wordplay.
'better' becomes 'cap' (both can mean to beat somebody else's attempt).
'money' becomes 'tin' (old-fashioned slang term for money).
'needed to secure' means one lot of letters goes inside another (insert letters are secured or held).
'tin' placed around 'a' is 'tain'.
'cap'+'tain'='CAPTAIN'
(Other definitions for captain that I've seen before include "Lead (a team)" , "Naval rank" , "US policeman" , "soldier" , "Naval commander" .)