Soldier's holding large weapon or seaman's tool (12)

'tool' is the definition.
(marlinespike is a kind of tool)

'soldier's holding large weapon or seaman's' is the wordplay.
I cannot really understand how this works, but
'large' could be 'l' (eg in clothes sizes) and 'l' is found in the answer.
'soldier's' could be 'marines' (I've seen this in other clues) and 'marines' is found within the leftover letters.
'weapon' could be 'pike' (pike is a kind of weapon) and 'pike' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...

Can you help me to learn more?