Large liquid expanse of hydrogen discharged from small African tree (3)
I believe the answer is:
sea
'large liquid expanse' is the definition.
'sea' can be an answer for 'expanse' (I've seen this in another clue). I am not certain of the 'large liquid' bit.
'hydrogen discharged from small african tree' is the wordplay.
I cannot really understand how this works, but
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is found within the answer.
The remaining letters 'ea' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for sea that I've seen before include "The Aegean, for example" , "Cod's home?" , "Large body of salt water" , "Adriatic, for example" , "Large expanse of water" .)