Trek (4)
(Other definitions for plod that I've seen before include "Tread wearily" , "Walk heavily and wearily" , "Noddy's police constable" , "Walk doggedly" , "coppers?" .)
'trek' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for hike that I've seen before include "Walking tour" , "Increase cost" , "Trek" , "Long, hard walk" , "Long ramble" .)
(Other definitions for star that I've seen before include "See 21" , "Distant sun" , "Celebrated performer" , "A .... called Henry (Roddy Doyle)" , "Five-pointed celestial body" .)