Crossing fen, got an outlandish form of transport (8)
I believe the answer is:
toboggan
'form of transport' is the definition.
(transport used in the snow)
'crossing fen got an outlandish' is the wordplay.
'crossing' indicates putting letters inside (to cross can mean to go over or around).
'fen' becomes 'bog' (I've seen this before).
'outlandish' is an anagram indicator.
'got'+'an'='gotan'
'gotan' anagrammed gives 'togan'.
'bog' going within 'togan' is 'TOBOGGAN'.
(Other definitions for toboggan that I've seen before include "Travel in it" , "Sled with boards curved up in front" , "Light sledge for sliding downhill" , "Frame for sliding on snow" , "Sliding vehicle" .)