Snapped a pencil in crossing (7)
I believe the answer is:
pelican
'crossing' is the definition.
(pelican crossing is a type of road crossing)
'snapped a pencil' is the wordplay.
'snapped' indicates anagramming the letters.
'a'+'pencil'='apencil'
'apencil' anagrammed gives 'PELICAN'.
'in' acts as a link.
(Other definitions for pelican that I've seen before include "Aquatic bird with pouch" , "Tropical bird" , "Large-billed waterbird" , "Large bird with enormous beak" , "Seabird having a large bill with a pouch for fish" .)