Sea bird nearly trapped in wild fen or swamp (6)
I believe the answer is:
engulf
'swamp' is the definition.
(I've seen this before)
'sea bird nearly trapped in wild fen' is the wordplay.
'sea bird' becomes 'gull' (gull is a kind of sea bird).
'nearly' means to remove the last letter.
'trapped in' is an insertion indicator.
'wild fen' becomes 'enf' (I can't explain this - if you can you should give a lot more credence to this answer).
'gull' with its final letter taken off is 'gul'.
'gul' put into 'enf' is 'ENGULF'.
'or' acts as a link.
Can you help me to learn more?
(Other definitions for engulf that I've seen before include "'Surround, overwhelm (6)'" , "Absorb, immerse" , "Swamp, overwhelm" , "Swallow up like wave" , "Flu gen (anag) - overwhelm" .)