Sailor on the border is full (5)
I believe the answer is:
abrim
'full' is the definition.
I know nothing about this answer so I can't tell whether this works.
'sailor on the border' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'on' means one lot of letters go next to another.
'the border' becomes 'rim' (I've seen this in other clues).
'ab'+'rim'='ABRIM'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for abrim that I've seen before include "Completely full" , "Spilling over" .)