Allocate a small token (6)
I believe the answer is:
assign
'allocate' is the definition.
(I've seen this in another clue)
'a small token' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'token' becomes 'sign' (I've seen this before).
'a'+'s'+'sign'='ASSIGN'
(Other definitions for assign that I've seen before include "Transfer (legal rights)" , "Set aside for a specific purpose" , "Allocate (a task or duty)" , "Allocate (duties to someone)" , "Delegate" .)