Small ice cream or snack (5)
I believe the answer is:
scone
'snack' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'small ice cream' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'ice cream' becomes 'cone' (cone can refer to an ice cream cone).
's'+'cone'='SCONE'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for scone that I've seen before include "Plain cake (for Scottish kings?)" , "Unsweetened cake" , "ancient Scottish settlement" , "Accompaniment for tea" , "A little cake" .)