Break one's neck catching tail with it (6)
I believe the answer is:
trendy
'with it' is the definition.
(both can mean fashionable)
'break one's neck catching' is the wordplay.
'break' becomes 'rend' (I've seen this in other clues).
'one's neck' becomes 'ty' (I can't explain this - if you can you should give a lot more credence to this answer).
'catching' indicates putting letters inside.
'rend' going inside 'ty' is 'TRENDY'.
'tail' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for trendy that I've seen before include "With it, a la mode" , "Consciously fashionable" , "Stylish" , "With-it" , "In vogue" .)