Hellish final scramble involving English sailors (8)
I believe the answer is:
infernal
'hellish' is the definition.
(I know that hellish can be written as infernal)
'final scramble involving english sailors' is the wordplay.
'scramble' indicates an anagram.
'involving' means one lot of letters goes inside another.
'english' becomes 'E' (abbreviation).
'sailors' becomes 'RN' (abbreviation for Royal Navy).
'final' anagrammed gives 'infal'.
'e'+'rn'='ern'
'infal' placed around 'ern' is 'INFERNAL'.
(Other definitions for infernal that I've seen before include "Devilish" , "Of the nether regions" , "Extremely annoying" , "To do with hell, or informally detestable" , "Hellish - damned" .)