Working on care for muscle attachment (6)
I believe the answer is:
tendon
'muscle attachment' is the definition.
(I've seen this before)
'working on care' is the wordplay.
'working' becomes 'on'.
'on' is a charade indicator (letters next to each other).
'care' becomes 'tend' (I've seen this before).
'on' after 'tend' is 'TENDON'.
'for' acts as a link.
(Other definitions for tendon that I've seen before include "Muscle-bone link" , "Strong band of tissue connecting muscles" , "Link between bone and muscle" , "Strong cord of tissue connecting muscle" , "Tissue cord connecting muscle to bone" .)