Some small amount I left in the till (5)
I believe the answer is:
until
'the till' is the definition.
(thesaurus)
'some small amount i left' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'UNTIL' is hidden in the letters of 'small amount i left'.
'in' acts as a link.
(Other definitions for until that I've seen before include "Up to that moment" , "As late as" , "As far as" , "Before a given time" , "Pending such time as" .)