Stop for a breather after half a year (6)
I believe the answer is:
arrest
'stop' is the definition.
(I know that stop can be written as arrest)
'a breather after half a year' is the wordplay.
'a breather' becomes 'rest' (I've seen this before).
'after' means one lot of letters go next to another.
'half a' suggests halving the letters.
'year' cut in half is 'ar'.
'rest' put after 'ar' is 'ARREST'.
'for' is the link.
(Other definitions for arrest that I've seen before include "Run in" , "Stop (on suspicion)" , "Collar" , "Take into legal custody" , "Cause to stop" .)