Covering miles — some flipping walk! (5)
I believe the answer is:
tramp
'walk' is the definition.
(I know that tramp is a type of walk)
'covering miles some flipping' is the wordplay.
'covering' is an insertion indicator.
'miles' becomes 'm' (common abbreviation).
'some' becomes 'part' (only part of something).
'flipping' says the letters should be written in reverse.
'm' placed within 'part' is 'pmart'.
'pmart' back-to-front is 'TRAMP'.
(Other definitions for tramp that I've seen before include "A boat; a vagrant" , "Itinerant" , "one unlikely ever to have a mortgage!" , "Down-and-out" , "The man on the street?" .)