Turning up, keep complaining over trap for seabird (6)
I believe the answer is:
gannet
'for seabird' is the definition.
(type of seabird)
'turning up keep complaining over trap' is the wordplay.
'turning up' is a reversal indicator.
'keep complaining' becomes 'nag' (I can't justify this - if you can you should give a lot more credence to this answer).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'trap' becomes 'net' (net is a type of trap).
'nag' written backwards gives 'gan'.
'gan'+'net'='GANNET'
Can you help me to learn more?
(Other definitions for gannet that I've seen before include "Act in accordance (with command)" , "Heavily built marine bird" , "Greedy person (colloq.); seabird" , "Large seabird, white with dark markings" , "Solan goose was this bird's former name" .)