Bundle of tissue in giant elm tangled (8)
I believe the answer is:
ligament
'bundle of tissue' is the definition.
(bundle of tissue in the body)
'giant elm tangled' is the wordplay.
'tangled' is an anagram indicator.
'giant'+'elm'='giantelm'
'giantelm' anagrammed gives 'LIGAMENT'.
'in' acts as a link.
(Other definitions for ligament that I've seen before include "Tissue which joins bones" , "What may get torn" , "What footballer may damage" , "sheet of tissue" , "Fibrous connective tissue" .)