Fish could be small kippers (8)
I believe the answer is:
snappers
'fish' is the definition.
(I've seen this before)
'small kippers' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'kippers' becomes 'nappers' (to kip is to sleep or nap).
's'+'nappers'='SNAPPERS'
'could be' is the link.
(Other definitions for snappers that I've seen before include "They casually photograph" , "marine fish" , "People photographing" .)