Spectacular gesture's most generous (7)
I believe the answer is:
largest
'most generous' is the definition.
('large' can be similar in meaning to 'generous')
'spectacular gesture's' is the wordplay.
'LARGEST' is hidden within the letters.
However, I am unsure how this is indicated.
(Other definitions for largest that I've seen before include "Superlatively extensive" , "Biggest" , "Most substantial" , "Extremely generous" , "Greatest in size" .)