Purchase beef after reduction (4)
I believe the answer is:
grip
'purchase' is the definition.
(I've seen this in another clue)
'beef after reduction' is the wordplay.
'beef' becomes 'gripe' (synonyms).
'after reduction' means to remove the last letter.
'gripe' with its final letter taken away is 'GRIP'.
(Other definitions for grip that I've seen before include "Seize interest" , "Hold fast" , "Take firm hold of travelling bag?" , "Control" , "Grasp tightly" .)