Place to gradually advance commitment (6)
I believe the answer is:
pledge
'commitment' is the definition.
(pledge is a kind of commitment)
'place to gradually advance' is the wordplay.
'place' becomes 'pl' (I've seen this in other clues).
'to gradually advance' becomes 'edge'.
'pl'+'edge'='PLEDGE'
(Other definitions for pledge that I've seen before include "Vow, affirm" , "Firm commitment" , "Give one's word" , "Plight" , "Promise or pawn" .)