Are breaking it in for him (5)
I believe the answer is:
artie
'him' is the definition.
'are breaking it in' is the wordplay.
'breaking' is an anagram indicator.
'in' indicates putting letters inside.
'it' is an anagram of 'ti'.
'are' going around 'ti' is 'ARTIE'.
'for' is the link.
(Other definitions for artie that I've seen before include "Man" , "- Shaw, US jazz clarinettist and bandleader" , "Shaw, perhaps?" , "Guy" , "-- Shaw, jazz musician" .)