Stagger catching oddly rugged and round fish (8)
I believe the answer is:
sturgeon
'fish' is the definition.
(sturgeon is a kind of fish)
'stagger catching oddly rugged and round' is the wordplay.
'stagger' becomes 'stun' (I've seen this before).
'catching' is an insertion indicator.
'oddly' indicates alternate letters (letters in the odd-numbered positions are used).
'and' is a charade indicator (letters next to each other).
'round' becomes 'o' (round can mean a round object).
The alternate letters of 'rugged' are 'rge'.
'rge'+'o'='rgeo'
'stun' going around 'rgeo' is 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "Egg producer" , "Something fishy here" , "producer of caviar" , "Caviar-producing fish" , "So urgent to find caviare-bearing fish" .)