Recall walker tiring in part in long journey on foot (4)
I believe the answer is:
trek
'long journey on foot' is the definition.
(I've seen this before)
'recall walker tiring in part' is the wordplay.
'recall' says the letters should be written backwards.
'in part' indicates a hidden word.
'kert' is hidden within 'walker tiring'.
'kert' reversed gives 'TREK'.
'in' is the link.
(Other definitions for trek that I've seen before include "Extended journey" , "Long hard journey on foot" , "Long walk, expedition" , "Long difficult walk" , "Tramp" .)