On return, keep catching fish — in this? (7)
I believe the answer is:
dragnet
'this?' is the definition.
The definition suggests a singular noun which matches the answer.
'on return keep catching fish' is the wordplay.
'on return' is a reversal indicator.
'keep' becomes 'tend'.
'catching' is an insertion indicator.
'fish' becomes 'gar' (gar is a kind of fish).
'tend' going around 'gar' is 'tengard'.
'tengard' written backwards gives 'DRAGNET'.
'in' is the link.
Can you help me to learn more?
(Other definitions for dragnet that I've seen before include "Granted, this may be an organised system of gathering in" , "hunt for suspect" , "Mesh drawn across river to catch fish" , "Comprehensive search" , "Systematic police search for wanted person" .)