Little thanks, at the end of the road (3)
I believe the answer is:
tad
'little' is the definition.
(both can mean a small amount)
'thanks at the end of the road' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'at the end of' indicates one should take the final letters.
The last letter of 'road' is 'd'.
'ta'+'d'='TAD'
(Other definitions for tad that I've seen before include "little boy" , "A small amount (colloq.)" , "Little bit" , "Modest amount" , "Smidgen" .)