Intractable objections raised principally by old sailors (8)
I believe the answer is:
stubborn
'intractable' is the definition.
(associated in meaning)
'objections raised principally by old sailors' is the wordplay.
'objections' becomes 'buts' (as in 'no ifs, no buts').
'raised' says the letters should be written in reverse (going up in a down clue).
'principally' says to take the initial letters.
'sailors' becomes 'RN' (abbreviation for Royal Navy).
The initial letters of 'by old' is 'bo'.
'buts' written backwards gives 'stub'.
'stub'+'bo'+'rn'='STUBBORN'
(Other definitions for stubborn that I've seen before include "Obstinate, tenacious" , "Wilful" , "Unreasonably unwilling to change" , "Showing dogged determination" , "Strong-willed" .)