Fish that's pale and a bit off (9)
I believe the answer is:
whitebait
'fish' is the definition.
(whitebait is a kind of fish)
'pale and a bit off' is the wordplay.
'pale' becomes 'white' (I've seen this before).
'and' says to put letters next to each other.
'off' is an anagram indicator.
'a'+'bit'='abit'
'abit' with letters rearranged gives 'bait'.
'white'+'bait'='WHITEBAIT'
'that's' is the link.
(Other definitions for whitebait that I've seen before include "Fish eaten in quantity" , "Small fried fish" , "Small edible fish" , "Young of herrings" , "Small silvery fish, the fry of herring" .)