Nothing to write home? Good opportunity (7)
I believe the answer is:
opening
'opportunity' is the definition.
(opening is a kind of opportunity)
'nothing to write home? good' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to' is a charade indicator (letters next to each other).
'write' becomes 'pen' ('pen' can be a synonym of 'write').
'home?' becomes 'in' ('he's home' can mean 'he's in').
'good' becomes 'g' (abbreviation).
'o'+'pen'+'in'+'g'='OPENING'
(Other definitions for opening that I've seen before include "Window of opportunity" , "Gateway - opportunity" , "Beginning, available job" , "First -- beginning" , "Aperture or first night" .)