Take head off pimple satisfactorily - it's bound to release all that viscous liquid
I believe the answer is:
oil well
'bound to release all that viscous liquid' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'take head off pimple satisfactorily' is the wordplay.
'take' becomes 'do' ('To take' a course is 'to do' a course).
'head off' means to remove the first letter.
'pimple' becomes 'il' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'satisfactorily' becomes 'well' ('well' can be a synonym of 'satisfactorily').
'do' with its initial letter taken off is 'o'.
'o'+'il'+'well'='OIL-WELL'
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for oil well that I've seen before include "Whence petroleum is extracted" , "Mineral bore" , "Maintenance advice for metal hinges" , "supporter of black economy?" , "What extracts riches" .)