Catch sight of son with trophy (4)
I believe the answer is:
spot
'catch sight of' is the definition.
(spotting is a kind of catching sight of)
'son with trophy' is the wordplay.
'son' becomes 's'.
'with' is a charade indicator (letters next to each other).
'trophy' becomes 'pot' (I've seen this before).
's'+'pot'='SPOT'
(Other definitions for spot that I've seen before include "Sight - site" , "Espy; mark" , "See; round mark" , "Notice - stain - pick out" , "Informally, catch sight of" .)