Spoor smell could expose new trail initially (5)
I believe the answer is:
scent
'spoor' is the definition.
(I've seen this in another clue)
'smell could expose new trail initially' is the wordplay.
'initially' suggests taking the first letters.
The initial letters of 'smell could expose new trail' is 'SCENT'.
(Other definitions for scent that I've seen before include "Distinctive odour" , "Perfume for the tracker" , "Number of clues" , "Distinctive aroma" , "Distinctive smell" .)