It conveys eggs over bridge, leaving area (7)
I believe the answer is:
oviduct
'it conveys eggs' is the definition.
'over bridge leaving area' is the wordplay.
'over' becomes 'o' (cricket abbreviation**).
'bridge' becomes 'viaduct' (viaduct is a kind of bridge).
'leaving' is a deletion indicator.
'area' becomes 'a' (maths abbreviation).
'viaduct' with 'a' taken out is 'viduct'.
'o'+'viduct'='OVIDUCT'
(Other definitions for oviduct that I've seen before include "Egg-laying tube" , "route for egg delivery" .)