Seeking perch, perhaps flapping, losing head (7)
I believe the answer is:
angling
'seeking' is the definition.
(angling is a kind of seeking)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for angling that I've seen before include "Walton practised it" , "seeking compliments, perhaps?" , "Fishing with rod and line" , "Fishing with hook and line" , "Pursuit with hook, line and sinker?" .)