Corporation worker beginning to get into routine (4,3)
I believe the answer is:
beer gut
'corporation' is the definition.
(I have seen 'large corporation' mean 'beer gut' so perhaps 'corporation' could also mean 'beer gut')
'worker beginning to get into routine' is the wordplay.
'worker' becomes 'bee' (I've seen this before).
'beginning to' suggests taking the first letters.
'into' means one lot of letters goes inside another.
'routine' becomes 'rut' (rut is a kind of routine).
The initial letter of 'get' is 'g'.
'g' inserted within 'rut' is 'rgut'.
'bee'+'rgut'='BEER GUT'
(Another definition for beer gut that I've seen is " large corporation".)