Get 50% off wrapping material that comes with strings attached (5)
I believe the answer is:
cello
'that comes with strings attached' is the definition.
(stringed instrument)
'get 50 off wrapping material' is the wordplay.
'get 50 off' suggests halving the letters (take 50 per cent off the word).
'wrapping material' becomes 'cellophane' (type of plastic for packaging food).
'cellophane' with half the letters taken is 'CELLO'.
(Other definitions for cello that I've seen before include "Viola's bigger brother?" , "Musical instrument like large violin held between knees" , "Casals' instrument" , "big fiddle?" , "Tortelier's instrument" .)