Complain because rum's gone up again? (6)
I believe the answer is:
murmur
'complain' is the definition.
(I know that murmur is a type of complain)
'because rum's gone up again?' is the wordplay.
I cannot quite see how this works, but
an anagram of 'rum' is 'mur' which is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for murmur that I've seen before include "Mumbled expression of malcontent" , "Mumble" , "Speak in a low voice, whisper" , "Abnormal sound made by heart" , "Speak softly or indistinctly" .)