Generous when loaned in extremes of poverty (6)
I believe the answer is:
plenty
'generous' is the definition.
(thesaurus)
'loaned in extremes of poverty' is the wordplay.
'loaned' becomes 'lent' ('lend' can be a synonym of 'loan').
'in' indicates putting letters inside.
'extremes of' means to remove the middle letters.
'poverty' with its middle taken out is 'py'.
'lent' put inside 'py' is 'PLENTY'.
'when' acts as a link.
(Other definitions for plenty that I've seen before include "More than enough" , "Amplitude or abundance" , "A lot" , "Many" , "Masses" .)