One backing search for shark (9)

I believe the answer is:

angelfish

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'shark' is the definition.
(angelfish is a kind of shark)

'one backing search' is the wordplay.
'one backing' becomes 'angel' (I can't justify this - if you can you should believe this answer much more).
'search' becomes 'fish' (fishing is a kind of searching).
'angel'+'fish'='ANGELFISH'

'for' is the link.

Can you help me to learn more?

(Other definitions for angelfish that I've seen before include "Brightly-coloured swimmer" , "shark" .)

I've seen this clue in The Independent.

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