Progressive Alliance restricts meat? (4)
I believe the answer is:
veal
'meat?' is the definition.
(veal is a kind of meat)
'progressive alliance restricts' is the wordplay.
'restricts' says the answer is hidden in the clue (the answer is held or restricted by the clue).
'VEAL' is hidden in the letters of 'progressive alliance'.
(Other definitions for veal that I've seen before include "Calf flesh" , "Type of meat" , "cuisine" , "meat, R [ROSE] maybe" , "Calf's flesh as food" .)