Inherited material evident at first in Swiss banker (6)
I believe the answer is:
genome
'inherited material' is the definition.
'evident at first in swiss banker' is the wordplay.
'at first' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'swiss banker' becomes 'gnome' (informal term for a banker, esp. one in Zurich).
The initial letter of 'evident' is 'e'.
'e' inserted into 'gnome' is 'GENOME'.
(Other definitions for genome that I've seen before include "What specifies all characteristics" , "Full chromosome set" , "Full set of chromosomes of an individual" , "Complete set of genetic material in the cell of an organism" , "Cocktail, borer" .)