One who loves me to wear jumper (5)
I believe the answer is:
romeo
'one who loves' is the definition.
(lover in Romeo and Juliet)
'me to wear jumper' is the wordplay.
'to wear' means one lot of letters goes inside another (to wear something is to be covered up by it).
'jumper' becomes 'roo' (short for kangaroo, something which jumps).
'me' put into 'roo' is 'ROMEO'.
(Other definitions for romeo that I've seen before include "Juliet's swain" , "Shakespearean lover" , "Ardent male lover" , "his tragedy one was late?" , "A loving character" .)