New singlet itches (7)
I believe the answer is:
tingles
'itches' is the definition.
(tingling is a kind of itching)
'new singlet' is the wordplay.
'new' indicates anagramming the letters.
'singlet' with letters rearranged gives 'TINGLES'.
(Other definitions for tingles that I've seen before include "Slight thrilling or stinging sensations" , "Frissons" , "Feels stinging sensation in singlet" .)