Small, meagre trail (5)
I believe the answer is:
spoor
'trail' is the definition.
(I've seen this before)
'small meagre' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'meagre' becomes 'poor' (I've seen this before).
's'+'poor'='SPOOR'
(Other definitions for spoor that I've seen before include "Animal track or scent" , "Beast's trail" , "Track of wild animal" , "Trace" , "24 [TRAIL]" .)