... and more than half of that's wrapped in tissue (5)
I believe the answer is:
sinew
'tissue' is the definition.
(sinew is a kind of tissue)
'and more than half of that's wrapped' is the wordplay.
I cannot quite see how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
'that's' could be 'ie' and 'ie' is found in the remaining letters.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for sinew that I've seen before include "Cord of tissue connecting muscle to bone" , "Tendon - ligament" , "It indicates strength" , "source of physical strength" , "power source" .)