Whale seen in mirror quality reflection (7)
I believe the answer is:
rorqual
'whale' is the definition.
(rorqual is a kind of whale)
'in mirror quality reflection' is the wordplay.
'in' indicates a hidden word.
'RORQUAL' can be found hidden inside 'mirror quality reflection'.
'seen' is the link.
(Other definitions for rorqual that I've seen before include "whalers' target" , "Whale with dorsal fin" , "Huge beast" , "Toothless creature" , "Finback whale" .)