Climb without a track (5)
I believe the answer is:
scent
'track' is the definition.
(both can mean a trace left by someone)
'climb without a' is the wordplay.
'climb' becomes 'ascent' (synonyms).
'without' indicates named letters should be taken away.
'ascent' with 'a' taken away is 'SCENT'.
(Other definitions for scent that I've seen before include "Bouquet" , "Animal smell" , "Whiff" , "Distinctive odour" , "Fragrance" .)