Bit of grouse - a precise cut - fit for the stomach (7)
I believe the answer is:
gastric
'for the stomach' is the definition.
(gastric means relating to the stomach)
'bit of grouse a precise cut' is the wordplay.
'bit of grouse' becomes 'ga' (I can't justify this - if you can you should give a lot more credence to this answer).
'a precise' becomes 'strict' (I've seen this before).
'cut' means to remove the last letter.
'strict' with its last letter taken off is 'stric'.
'ga'+'stric'='GASTRIC'
'fit' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for gastric that I've seen before include "Abdominal" , "of the corporation?" , "Pertaining to the stomach" , "Stomachic" , "Intestinal" .)