Skinned tuna left to be distributed as a quantity of fish (6)
I believe the answer is:
netful
'a quantity of fish' is the definition.
(amount of fish caught in a net)
'skinned tuna left to be distributed' is the wordplay.
'skinned' says to take the centre.
'to be distributed' indicates an anagram.
The central letters of 'tuna' are 'un'.
'un'+'left'='unleft'
'unleft' with letters rearranged gives 'NETFUL'.
'as' acts as a link.
(Other definitions for netful that I've seen before include "A good catch of fish" , "lot of goals?" , "quite a catch" .)