School went ahead with winter transport (4)
I believe the answer is:
sled
'winter transport' is the definition.
(I've seen this in another clue)
'school went ahead' is the wordplay.
'school' becomes 'S'.
'went ahead' becomes 'led' (led the way).
's'+'led'='SLED'
'with' acts as a link.
(Other definitions for sled that I've seen before include "American toboggan" , "Sleigh" , "Winter transport" , "Sledge" , "Goods vehicle" .)