Slim son who loans money (7)
I believe the answer is:
slender
'slim' is the definition.
(I know that slim can be written as slender)
'son who loans money' is the wordplay.
I cannot really see how this works, but
'son' could be 's' (genealogical abbreviation for son) and 's' is located in the answer.
'money' could be 'l' (L can mean 'pounds') and 'l' is present in the answer.
The remaining letters 'ender' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for slender that I've seen before include "Ann Page's suitor" , "Meagre" , "inadequate" , "associated with 7 [MEANS] suggests modest income" , "Barely sufficient; thin" .)