Charles invests in bonds (6)
I believe the answer is:
chains
'bonds' is the definition.
(I know that chain is a type of bonds)
'charles invests in' is the wordplay.
'charles' becomes 'Chas' (shortened form).
'invests' means one lot of letters goes inside another (inserted letters are invested).
'chas' placed around 'in' is 'CHAINS'.
(Other definitions for chains that I've seen before include "Metal ropes with links (6)" , "Restriction" , "Cash in for manacles and irons" , "Fetters" , "Metal shackles for hands or legs" .)