Throwing loops of rope on board, pack square boxes first for once (4,6)
I believe the answer is:
deck quoits
'throwing loops' is the definition.
I know nothing about this answer so I can't tell whether this works.
'of rope on board pack square boxes first for once' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is located in the answer.
'pack' could be 'deck' (deck is a kind of pack) and 'deck' is located in the answer.
'square' could be 't' (a T-Square is a technical drawing instrument) and 't' is found in the answer.
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for deck quoits that I've seen before include "recreation on liner?" , "game on board" .)