Nothing back at Gateshead! Just fish! (4)
I believe the answer is:
ling
'just fish' is the definition.
'ling' can be an answer for 'fish' (thesaurus). I'm not sure about the 'just' bit.
'nothing back at gateshead' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'back' shows that the letters should be reversed in order.
'at' is a charade indicator (letters next to each other).
'gateshead' becomes 'g' (head letter of 'gates').
'nil' in reverse letter order is 'lin'.
'lin'+'g'='LING'
Can you help me to learn more?
(Other definitions for ling that I've seen before include "Common heather" , "Slender food fish" , "Fish of the cod family" , "Burbot" , "Heather - fish" .)