Fish from middle of jetty beside Waterloo (5)
I believe the answer is:
trout
'fish' is the definition.
(trout is a kind of fish)
'middle of jetty beside waterloo' is the wordplay.
'middle of' means to look at the middle letters.
'beside' means one lot of letters go next to another (I've seen this in other clues).
'waterloo' becomes 'rout' (I've seen this in other clues).
The central letter of 'jetty' is 't'.
't'+'rout'='TROUT'
'from' is the link.
(Other definitions for trout that I've seen before include "Freshwater game fish" , "unpleasant old woman" , "Fish - old harridan" , "Tickled fish?" , "Irritating old person" .)