Hold on tight having caught fish (5)
I believe the answer is:
cling
'hold on tight' is the definition.
(I've seen this before)
'caught fish' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'fish' becomes 'ling' (ling is a kind of fish**).
'c'+'ling'='CLING'
'having' is the link.
(Other definitions for cling that I've seen before include "Hold on tightly, be dependent" , "fast" , "Hold on as for dear life" , "Hold on tightly, refuse to abandon" , "Stick - tinkle" .)