Generous volunteer? (6)
I believe the answer is:
tender
This clue is a double definition.
'generous' is the first definition.
(tender can mean generous or kind)
'volunteer?' is the second definition.
(tender can mean to offer or volunteer)
(Other definitions for tender that I've seen before include "Offer for acceptance" , "Fragile" , "A gentle kind of bid" , "Youthful" , "'Soft, sensitive offer? (6)'" .)