Source of funds, somewhat bigger than a piggy bank? (4,3)
I believe the answer is:
cash cow
'source' is the definition.
(I have seen 'source of profit' mean 'cash cow' so perhaps 'source' could also mean 'cash cow')
'funds somewhat bigger than a piggy bank?' is the wordplay.
I cannot really understand how this works, but
'funds' could be 'cash' (both can mean money) and 'cash' is located in the answer.
The remaining letters 'cow' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for cash cow that I've seen before include "Money-maker" , "E.g. business milked for money" , "Saw choc (anag.); steady investment" , "Steady income provider" , "Money-spinning business" .)