Snail set off carrying load (8)
I believe the answer is:
escargot
'snail' is the definition.
(escargot means an edible snail)
'set off carrying load' is the wordplay.
'off' is an anagram indicator.
'carrying' means one lot of letters goes inside another.
'load' becomes 'cargo' (synonyms).
'set' with letters rearranged gives 'est'.
'est' placed around 'cargo' is 'ESCARGOT'.
(Other definitions for escargot that I've seen before include "An edible snail from France" , "mollusc, from Paris" , "French food" , "Edible snail (from Fr.)" , "slow food?" .)