One hoping to net Boston assassin straight away (6)
I believe the answer is:
angler
'one hoping to net boston assassin straight away' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'one' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'an' (I've seen this in other clues) and 'an' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for angler that I've seen before include "Fisher with rod and line" , "Hook and line fisherman" , "who looks for compliments" , "person hoping to catch fish" , "Fisher with hook and line." .)