Returning at times to get one form of transport (4)
I believe the answer is:
taxi
'transport' is the definition.
(taxi is a kind of transport)
'returning at times to get one form' is the wordplay.
'returning' says the letters should be written in reverse.
'times' becomes 'x' (multiplication sign).
'to get' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'form' indicates an anagram.
'at' written backwards gives 'ta'.
'x' after 'i' is 'ix'.
'ix' with letters rearranged gives 'xi'.
'ta'+'xi'='TAXI'
'of' acts as a link.
(Other definitions for taxi that I've seen before include "people carrier?" , "Vehicle with a meter" , "type of vehicle" , "Move along a runway" , "Danny DeVito sitcom" .)