Explanation of how to make the beer go further! (9)
I believe the answer is:
rationale
'explanation' is the definition.
(rationale is a kind of explanation)
'how to make the beer go further' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'beer' could be 'ale' (type of beer) and 'ale' is found within the answer.
'further' could be 'on' (synonyms) and 'on' is found within the answer.
The remaining letters 'rai' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for rationale that I've seen before include "Logical reason for action" , "justification" , "The logical basis of some thing or action" , "Logical reasons (for action)" , "Philosophy" .)