Band ultimately entering part of joint? (6)
I believe the answer is:
tendon
'band ultimately entering part of joint?' is the definition.
'tendon' can be an answer for 'band' (I have seen 'Fibrous band ' mean 'tendon' so perhaps 'band' could also mean 'tendon'). I'm unsure of the 'ultimately entering part of joint?' bit.
'band ultimately entering part of joint?' is the wordplay.
'ultimately' says to take the final letters.
'entering' means one lot of letters goes inside another.
'part of joint?' becomes 'tenon' (I've seen this in other clues).
The last letter of 'band' is 'd'.
'd' put into 'tenon' is 'TENDON'.
(Other definitions for tendon that I've seen before include "Strong band of tissue connecting muscles" , "It's attaches tissue to bone" , "Tissue connecting a muscle with its bony attachment" , "Muscle-bone link" , "personal connecting link" .)