Hopeless Irish sunburned sailor in melee at sea (12)
I believe the answer is:
irredeemable
'hopeless' is the definition.
(I've seen this before)
'irish sunburned sailor in melee at sea' is the wordplay.
'irish' becomes 'IR' (abbreviation).
'sunburned' becomes 'red' (I've seen this in another clue).
'sailor' becomes 'ab' (abbreviation for able seaman).
'in' indicates putting letters inside.
'at sea' indicates anagramming the letters.
'melee' anagrammed gives 'eemle'.
'ab' placed into 'eemle' is 'eemable'.
'ir'+'red'+'eemable'='IRREDEEMABLE'
(Other definitions for irredeemable that I've seen before include "Not able to be saved" , "Without a pawn ticket, things can be so" , "hopeless" , "Beyond being saved" .)