Fish for £1 to no good end (4)
I believe the answer is:
ling
'fish' is the definition.
(ling is a kind of fish)
'ps1 to no good end' is the wordplay.
I cannot quite see how this works, but
'no' could be 'n' (common abbreviation) and 'n' is located in the answer.
'good' could be 'g' (abbreviation) and 'g' is present in the answer.
The remaining letters 'li' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for ling that I've seen before include "Fish of the cod family" , "Heather - fish" , "Cod-like fish" , "Swimmer" , "Burbot" .)