Change a singlet and sparkle (7)
I believe the answer is:
glisten
'sparkle' is the definition.
('glisten' can be a synonym of 'sparkle')
'change a singlet' is the wordplay.
'change' is an anagram indicator.
'singlet' anagrammed gives 'GLISTEN'.
'and' is the link.
(Other definitions for glisten that I've seen before include "Shine like something wet" , "Singlet (anag.); tingles (anag.)" , "Glow from reflection" , "Reflect" , "Shine or sparkle wetly" .)