Wind - endless ploy of the stomach (7)
I believe the answer is:
gastric
'of the stomach' is the definition.
(I've seen this in another clue)
'wind endless ploy' is the wordplay.
'wind' becomes 'gas' (synonyms).
'endless' means to remove the last letter.
'ploy' becomes 'trick' (I've seen this before).
'trick' with its final letter taken off is 'tric'.
'gas'+'tric'='GASTRIC'
(Other definitions for gastric that I've seen before include "Relating to or involving the stomach" , "affecting stomach" , "Pertaining to the stomach" , "Stomachic" , "touching stomach" .)