Like meringue, say, with glossy exterior (4)
I believe the answer is:
eggy
'like meringue' is the definition.
(I've seen this in another clue)
'say with glossy exterior' is the wordplay.
'say' becomes 'eg' (both can mean 'for example').
'with' means one lot of letters go next to another.
'exterior' suggests removing the centre.
'glossy' with its centre taken out is 'gy'.
'eg'+'gy'='EGGY'
(Other definitions for eggy that I've seen before include "Like things hens lay" , "Like part of breakfast" , "Like an omelette" , "with a sulphurous niff?" , "Soaked in hens' produce" .)