Show agreement to carry about a thousand small sponges (5,5)

'small sponges' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'show agreement to carry about a thousand' is the wordplay.
I cannot really understand how this works, but
'show' could be 'fair' (fair is a kind of show) and 'fair' is found within the answer.
'about' could be 'ca' (abbreviation for 'circa') and 'ca' is found in the answer.
'thousand' could be 'k' (synonyms) and 'k' is located in the answer.
'agreement' could be 'yes' and 'yes' is found within the remaining letters.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?