Small distances for beams (6)
I believe the answer is:
smiles
'beams' is the definition.
(I've seen this before)
'small distances' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'distances' becomes 'miles' (I've seen this in another clue).
's'+'miles'='SMILES'
'for' acts as a link.
(Other definitions for smiles that I've seen before include "Gives visible sign of pleasure" , "Beams, grins" , "Shows signs of pleasure or amusement" , "Facial expressions showing pleasure" , "expresses pleasure" .)