Live within one’s means (4,4,4)
I believe the answer is:
make ends meet
'live within one's means' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for make ends meet that I've seen before include "unite extremists" , "Just have enough income" , "The Channel Tunnel consortium had to" , "Live within one's income" , "stay solvent" .)