Wrath of fisherman losing line (5)
I believe the answer is:
anger
'wrath' is the definition.
(synonyms)
'fisherman losing line' is the wordplay.
'fisherman' becomes 'angler' (angler is a kind of fisherman).
'losing' indicates named letters should be taken away.
'line' becomes 'l' (used when specifying particular lines from a poem).
'angler' with 'l' taken out is 'ANGER'.
'of' acts as a link.
(Other definitions for anger that I've seen before include "Strong displeasure" , "There's fury" , "Annoyance, displeasure" , "Feeling of vexation" , "Hack off" .)