Regularly leaving by five, glad to make return (5)
I believe the answer is:
yield
'return' is the definition.
(I know that return can be written as yield)
'regularly leaving by five glad' is the wordplay.
'regularly leaving' means one should take alternating letters (letters left out at regular intervals).
'by'+'five'+'glad'='byfiveglad'
The alternating letters of 'byfiveglad' are 'YIELD'.
'to make' is the link.
(Other definitions for yield that I've seen before include "Bring forth" , "Concede - product" , "Submit; produce" , "earnings" , "Chicken out" .)