Let loose energy and flatulate vaporous emission! (4,3,5)
I believe the answer is:
blow off steam
'flatulate vaporous emission' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'let loose energy' is the wordplay.
I cannot really see how this works, but
'energy' could be 'steam' (I've seen this before) and 'steam' is located in the answer.
'let loose' could be 'low' (lowing is a kind of letting loose) and 'low' is present in the answer.
The remaining letters 'boff' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'and' acts as a link.
Can you help me to learn more?
(Another definition for blow off steam that I've seen is " Release pent-up emotions".)