Sea cucumber’s flavour enthrals agent (7)
I believe the answer is:
trepang
'sea cucumber's' is the definition.
(trepang is a kind of sea cucumber)
'flavour enthrals agent' is the wordplay.
'flavour' becomes 'tang' (synonyms).
'enthrals' indicates putting letters inside.
'agent' becomes 'rep' (short for representative).
'tang' going around 'rep' is 'TREPANG'.
(Other definitions for trepang that I've seen before include "Sea cucumber" , "Chinese delicacy" , "Chinese food" .)