Wheels on a New York taxi may be so worn out (5)
I believe the answer is:
Here is my best explanation:
'worn out' is the definition.
('tire' can be a synonym of 'wear out')
'wheels on a new york taxi may be' is the subsidiary indication.
I cannot quite understand how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is present in the answer.
The remaining letters 'tid' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'so' is the link.
(Other definitions for tired that I've seen before include "Worn out", "In need of rest", "knackered", "Physically or mentally weary", "Drowsy", "In need of sleep", "Fatigued, weary", "Exhausted", "exhausted" and "Whacked".)