Untouchable alpha gets reputation aboard boat (6,3)
I believe the answer is:
sacred cow
'untouchable' is the definition.
(I've seen this in another clue)
'alpha gets reputation aboard boat' is the wordplay.
I cannot quite understand how this works, but
'alpha' could be 'a' (phonetic alphabet: alpha, bravo, charlie etc.) and 'a' is found in the answer.
'reputation' could be 'cred' (I've seen this in another clue) and 'cred' is located in the answer.
'boat' could be 'scow' (scow is a kind of boat) and 'scow' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sacred cow that I've seen before include "Hallowed bovine in India or revered institution" , "Person, custom, etc unreasonably held to be beyond criticism" , "Something bovine above criticism?" , "Person or institution held to be above criticism" , "Institution not to be criticised" .)