Be better than what’s caught in river and lake (5)
I believe the answer is:
excel
'be better than' is the definition.
(I've seen this before)
'caught in river and lake' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'in' indicates putting letters inside.
'river' becomes 'exe' (River Exe).
'and' is a charade indicator (letters next to each other).
'lake' becomes 'L' (geographical abbreviation).
'c' placed into 'exe' is 'exce'.
'exce'+'l'='EXCEL'
'what's' is the link.
(Other definitions for excel that I've seen before include "Be very good at, better than others" , "Do really well, outshine others" , "Be pre-eminent" , "Eclipse" , "Distinguish oneself - XL" .)