Fish eater given fresh plaice at the Nag's Head (7)
I believe the answer is:
pelican
'fish eater' is the definition.
'fresh plaice at the nag's head' is the wordplay.
'fresh' is an anagram indicator (a fresh re-ordering of the letters).
'at' means one lot of letters go next to another.
'head' indicates taking the first letters.
The first letter of 'nags' is 'n'.
'plaice' with letters rearranged gives 'pelica'.
'pelica'+'n'='PELICAN'
'given' acts as a link.
(Other definitions for pelican that I've seen before include "one with huge bill" , "Large water bird" , "Seabird with a large pouched bill" , "Large-billed seabird" , "Aquatic bird with pouch" .)