Signs one's worried about source of money (5)
I believe the answer is:
omens
'signs' is the definition.
(omen is a kind of sign)
'one's worried about source of money' is the wordplay.
'worried' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'source of' says to take the initial letters.
The first letter of 'money' is 'm'.
'ones' anagrammed gives 'oens'.
'oens' placed around 'm' is 'OMENS'.
(Other definitions for omens that I've seen before include "Prognostications" , "Signs of things to come" , "Signs or warnings for the future" , "Harbingers, portents" , "Auguries" .)