Alternative: let C and S exchange wealth (8)
I believe the answer is:
resource
'wealth' is the definition.
(thesaurus)
'alternative let c and s exchange' is the wordplay.
I cannot quite see how this works, but
'c' is within the answer.
's' could be 'es' (es or ess is the spelling of the letter's name) and 'es' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for resource that I've seen before include "Facility" , "Provide with stock/assets" , "Reserve to draw upon when needed" , "A supply of materials" , "Available supply reserve" .)