A sailor got it slightly (1,3)
I believe the answer is:
a bit
'slightly' is the definition.
(I've seen this before)
'a sailor got it' is the wordplay.
'a sailor' becomes 'ab' (abbreviation for able seaman).
'got' means one lot of letters go next to another.
'ab'+'it'='A BIT'
(Other definitions for a bit that I've seen before include "Somewhat" , "Rather" , "Slightly" , "fairly?" , "to some extent" .)