Depend on me only (6)
I believe the answer is:
merely
'only' is the definition.
(merely can mean only or simply)
'depend on me' is the wordplay.
'depend' becomes 'rely' (to depend on someone is to rely on them).
'on' is a charade indicator (letters next to each other).
'rely' after 'me' is 'MERELY'.
(Other definitions for merely that I've seen before include "'Only, and nothing more (6)'" , "Just one" , "Simply - only" .)