Beginning to skid on inadequate track (5)
I believe the answer is:
spoor
'track' is the definition.
(spoor is a kind of track)
'beginning to skid on inadequate' is the wordplay.
'beginning to' says to take the initial letters.
'on' says to put letters next to each other.
'inadequate' becomes 'poor' ('poor' can be a synonym of 'inadequate').
The first letter of 'skid' is 's'.
's'+'poor'='SPOOR'
(Other definitions for spoor that I've seen before include "Animal track or scent" , "Beast's trail" , "24 [TRAIL]" , "Animal's track or scent" , "Trace" .)