Fixed price: English prescription (6)
I believe the answer is:
recipe
'prescription' is the definition.
(I've seen this before)
'fixed price english' is the wordplay.
'fixed' indicates an anagram.
'english' becomes 'e' (abbreviation**).
'price' is an anagram of 'recip'.
'recip'+'e'='RECIPE'
(Other definitions for recipe that I've seen before include "Directions for cooking the turkey e.g." , "Directions for making a dish" , "Kitchen instructions" , "Directions for making food etc" , "Formula for making something" .)