Last bit of orange put in port? Bliss! (6)
I believe the answer is:
heaven
'bliss' is the definition.
(I've seen this before)
'last bit of orange put in port?' is the wordplay.
'last bit of' suggests the final letters.
'put in' indicates putting letters inside.
'port?' becomes 'haven' (both can mean a place of safety).
The last letter of 'orange' is 'e'.
'e' inserted into 'haven' is 'HEAVEN'.
(Other definitions for heaven that I've seen before include "The abode of God in many religions" , "State of happiness" , "Elysium, Nirvana" , "Paradise - supreme happiness" , "Nirvana, paradise" .)