Good to leave swollen toe unit - that’s obvious (7)
I believe the answer is:
outward
'obvious' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for outward that I've seen before include "Towards the exterior" , "Away from port" , "Externally facing" , "Young person thus bound" , "Apparent" .)