Struggle helplessly seeing line adopted by father (8)
I believe the answer is:
flounder
'struggle helplessly' is the definition.
(I've seen this in another clue)
'line adopted by father' is the wordplay.
I cannot quite see how this works, but
'line' could be 'l' (used when specifying particular lines from a poem) and 'l' is located in the answer.
'father' could be 'founder' (synonyms) and 'founder' is found in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'seeing' is the link.
Can you help me to learn more?
(Other definitions for flounder that I've seen before include "Have difficulty" , "Fish; stagger clumsily" , "Struggle in water" , "thrash around wildly" , "Struggle clumsily - flatfish" .)