Notice small trophy (4)
I believe the answer is:
spot
'notice' is the definition.
(spot can mean to notice or observe)
'small trophy' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'trophy' becomes 'pot' (type of trophy).
's'+'pot'='SPOT'
(Other definitions for spot that I've seen before include "[NIGHTCLUB]" , "Notice - fictional puppy" , "station" , "Difficult situation" , "Espy; mark" .)