He drops a line in fury about first love (6)
I believe the answer is:
angler
'he drops a line' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'fury about first love' is the wordplay.
'fury' becomes 'anger' (I've seen this before).
'about' means one lot of letters goes inside another.
'first love' becomes 'l' (1st letter of 'love').
'anger' placed around 'l' is 'ANGLER'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for angler that I've seen before include "Hook and line fisherman" , "person hoping to catch fish" , "I cast Rod" , "A rod and line fisherman" , "I may do casting" .)