Having knocked back drink after drink, speak indistinctly (6)
I believe the answer is:
murmur
'speak indistinctly' is the definition.
(synonyms)
'having knocked back drink after drink' is the wordplay.
'having knocked back' shows that the letters should be reversed in order.
'drink' becomes 'rum' (rum is a kind of drink).
'after drink' becomes 'rum' (rum is a kind of drink. I am not sure about the 'after' bit.).
'rum'+'rum'='rumrum'
'rumrum' backwards is 'MURMUR'.
Can you help me to learn more?
(Other definitions for murmur that I've seen before include "Little noise" , "Low, indistinct speech" , "Soft voices (of discontent)" , "Subdued complaint" , "Quietly spoken utterance; heart defect" .)