Spry individual ends in senility (5)
I believe the answer is:
agile
'spry' is the definition.
(I've seen this before)
'individual ends in senility' is the wordplay.
'ends' means to remove the middle letters.
'in' is an insertion indicator.
'senility' becomes 'age' (I've seen this in other clues).
'individual' with its centre taken out is 'il'.
'il' put within 'age' is 'AGILE'.
(Other definitions for agile that I've seen before include "Quick and easy-moving" , "Limber" , "Mentally acute" , "Lithely moving" , "Quick in movement" .)